As much as I want them to find a miracle cure, I don't know if it fits with the theme either. CDPR says their committed to the future of the ip. Personally, I think it would be nice to explore the universe a bit more instead of such a personal story. What do you think. It would be nice to explore thus universe without a ticking time bomb in your head though.
Personally, I think the whole timebomb in your head without any cure, was a huge mistake in an open-world game like this.
This obviously goes a bit deeper, because they wanted Silverhand in the story, personally I don't mind Silverhand being there, but I don't think he adds a lot to the story, which couldn't have been there without him or could even have been done much better.
If they wanted to keep the timebomb plot thing, they should have made it so one of the characters you care for was the one you were trying to save, such as Jackie or maybe another newly created character, V's sister or brother.
The main issue with what they have done with the story is that they create a false feeling of tension. You as a player are constantly reminded to hurry up and get shit done or you will die. But on the other hand, you as a player just want to enjoy the city and see what it has to offer and be a badass merc finding cool stuff and upgrading your gear, buying some cars etc. at your own pacing.
But this creates a massive conflict, between the story and what the player want. And in order to play the game as you would like, you end up having to ignore a huge part of the story and simply pretend that it isn't there.
How they could have solved it
If we assume that it was Jackie that was suffering from the timebomb, I think this would work, given how fast people got attached to him and had they spent a bit more time on him it would have worked even better.
But what they could have done, was to design the game around saving his life, and you have all these corporations, people, gangs etc. that you could interact with in order to try to find a cure. The tension in the game could come from you as a player making actual choices, some good and some bad, depending on what you do, Jackie could eventually end up dying or he might survive in various stages. So the ultimate good ending would be Jackie recovering 100%, another he ends up with a fried brain in a wheelchair or hospital or whatever and in the worse case he would end up dying as a result of the player's actions.
In that case, you would have some very meaningful choices to make, they could even make it so if you do certain things others wouldn't be possible to really push the player to feel the effect of their choices.
They could also have made a lot of random quests about picking up leads or as a side thing to other quests. So for instance, if you as a player have to find some information about a person that might be able to help Jackie or have some important information, you could gather intel on them to figure out where they are etc. This could have been added to the game in a way so it supported the open world design, it would make sense for V to scout locations looking for clues and intel. Maybe some of the fixers know something but they won't help you, because they don't trust you, so you have to earn reputation first.
If they really wanted Silverhand in the game, they could either have added something which would let V see him, some special device to interact with him, in which case he would show up once you are on missions with Jackie or alternatively they could have made Jackie slowly change personality over the cause of the game, and show how he is clearly fighting with a split personality.
Leaving the player with no good endings and a feeling of urgency in an open-world game is a terrible choice in my opinion when this could be done so you as a player can see how your good or bad decision screws up people around you.
You have a lot of characters invested in Jackie, such as his former gang, his mother, Misty, Yourself, Vic and they could add more if needed. But seeing their reactions to what you do and having to deal with that, is a lot more interesting in my opinion than it only affects oneself.
And when the story is eventually over, whatever the outcome, you could still play on simply enjoying an open-world experience as a Merc. It would also be much easier to expand V's story.
At least to me, that would have made for a much better experience.