His death is inevitable, and this will never change, I don't see feeling in investing more in a character that can't bring much of the Cyberpunk universe, to so many things that have more potential than Jackie.
When you don't have the time or the mood to add more code and more voice acting, you kill characters. This time, I'm pretty sure it was time, especially since they did say that there are other paths you can take in The Heist, didn't they? So the inevitability of Jackie's death hangs on one reply from Delamain - oh, and by the way! Did you notice that your odds of success are presented to you on your way to the Konpeki? The destination written on the chair screens is "No Tell Motel" (another bitchslap to the players right there, those yet unware of how shit will go down. I mean... they could've at least put Konpeki Plaza on your first ride... talking about spoilers, pfft!).
Oh, but you have a lot of the CP universe in this game! In text format... All those shards you get to read and then have a shit time shuffling through? Yeah, there is quite a bit there. I kept saying they could've made the big corpos relevant instead of keeping them all as a footnote (hell! even Saka's just a plot carriage and nothing else). You hear about what Saka's doing in your timeline during a quest, you get to read a lot more about it... but that's it. You also read a lot about what Militech's doing, you can even postulate they're the ones hunting down Max, but that's that... Everything Militech in CP2077 is for decoration purposes (granted, the destroyable kind, but still only decoration).
Back to Jackie, I'm quite sure they had some bits prepared, but unfinished - from the time they were advertising CP2077 as a RPG, not... looter-shooter. And if you look at other RPGs - say DO or ME - you'd notice that your interaction with your friends doesn't stop when their story arc ends. Either because you end up having them as a perma team member (be it for their skill set or their witty comments during missions) or because you can get to chat'em up every now and then. In CP, something like this barely happens with Judy, but Panam will have no reaction as your conditions worsens and you progress towards your inevitable loop point. This makes the relationships shallow af (because nothing's built on enough aside from Johnny, characters, factions, you name it) and has a great contribution in making the main story quite unimportant - even if the biggest kick in the nuts is the "Ok, one more gig" effect of send you flying through time.
Delamain refuses to go anywhere but the 'No Tell Motel' as per orders and Jackie has the chip. So yeah it would require changes to the story to facilitate changes to jackie's state.
Most of the V endings could be pulled together akin to the base game lifepaths from their epilogue states.
Delamain saves you when taken to Vik by Goro, for example. For the branching outcome, 2 lines of Delamain's dialogue need to be altered. And, obviously a couple of yours, where you might say "If he's to have a chance at making it at all, Vik's the one that can give it to him, take him there" or "If he's to die, better it happens with his family". I'm pretty sure that if the game would've released when it was ready, not when the leadership stomped their foot, we wouldn't have had this conversation. CDPR can make good stories and good characters. The paper-thin ones we have in CP2077 are the collaterals of rushing the game out the door in true big corpo fashion. Hell! the way the universe is revealed to us is soooo akin to how Bethesda thought players would like to discover FO76's one. Reading shit in an empty world
The endings need not be pulled together. At all. Each can lead to other bits of the story unfolding, you know, like in good ol' TW2 fashion. I remember some developer saying at some point that a player might not be able or willing to go through all possible paths in the game, but they will put them there anyway. But there are changes - big ones - that need to happen if we're to actually keep a consistent timeline.
Panam's ending shouldn't physically take place 2 km away from NC. You decided to leave, so be gone! move the fuckin' tunnel and the lake out of NC's surroundings!. You're done with the merc life on that path, gonna settle down have a kid or 5 - or maybe scroll bd's till the bitter end. Point of no return has to mean something, after all. The Aldecaldos are hunted down after the stunt, so there's no logic in having him linger around NC either. No, if you're to somehow be reinserted into the game on that path, it's on a completely different location, mostly having to deal with the Wraiths if anything and pretty hard to convince those would somehow bring you back to NC. Unless the devs would choose to make another collage of your time with the Aldecaldos and make more characters irrelevant.
On a side note, Panam's ending could put a character on the nomad lifepath. Even if, story wise, there's little to build on from there.
The logical choice, Johnny's ending, one even built on in the game, again has not much ground to run on, if the outro stays the same. But say it happens! You'd play as another character, if anything, making the whole character creation even more irrelevant, making your dialogue choices pointless... even if Johnny would have at least some motivation to return to NC, to continue eroding the corporations there - not that they wouldn't be present everywhere else. However, to land on this path you did cause a pretty big ruckus, so again, a collage would be needed to show what you've been doing for a few years as Johnny, before returning to NC. Disconnecting you from the character completely - as those actions are in no way reflecting your own choices or playstyle.
Side note, Johnny's ending is probably the best to continue the solo character class, as he does have this outstanding conflict with all the big corpos.
Choosing to take up the 6 months gauntlet in the Rogue endings is horrible, as there's nothing left for you to do, aside from the mcguffin that has you bound for the Crystal Palace. You're way above all "major leagues". Nothing can be added to make your existence more relevant in the game's universe.
As a side note that can also be easily applied to all other endings, the biochip's still in V's head, the action takes place in the bowels of where it was made, so just writing your engram on it would kick it into altering your body again to prepare it for yourself. So yeah, there's that. Easy way out for V.
I didn't play the Saka ending, but the lore and the info you have in the game about the going-ons there makes this a good launch pad for continuing the game. Hell even giving you the choice to either helping the corporation to exact vengeance for what has happened in 2023 (talking about Militech nuking NC and blaming it on you) or to destroy them from the inside with the help of whoever's left standing that would be willing to do that (and, funny enough, all are, ey?)
I consider the way CDPR pulled all the lifepath on the very same rail a dick move. Another pointless character choice, with no depth and no effects on the main story whatsoever. Having this happen again at the end would be probably worse than just kicking you back through time. 400 hours in the game and I'm yet to have that feeling of pride and accomplishment, 'cause nothing I did was a reflection of my choices, even less so of my actions (seeing how whatever choices I actually made proved to be irrelevant - aside from the ones on the roof)...
TL;DR Jackie's story can be expanded easier than any other aspect, bringing the game a bit closer to the promised, meaningful choices, rpg. I agree that there are bigger fishes to be caught out there, with more weight in the CP universe than a random, minor league, NC merc. But another minor league merc in NC is our character. We kept trying (or not, depending on one's playstyle) to make friends, but CDPR didn't allow for that. We kept trying to make meaningful choice, but, again, we weren't allowed till the bitter end to do that either. I think Jackie's story could be a small step for us (seeing how it happens in Act 1 and all that), but a huge leap for them to correct that. Proof they didn't really shit on their promises. And, why not, that we might expect more meaningful choices to be introduced with other patches and dlcs.