I don't think there's anything that can "fix" the game for me, it's a pretty good game as it stands anyway.
I do have some ideas that could have taken the game from "pretty good" to "very good" for me, though, so I figure I'll go ahead and share them. For me, the main aspects that I think the game could have realistically done better - given the overall design approach CDPR took - would be more impact of the lifepath systems on the game and better-packaged side content.
One obvious area that to me seems like a perfect opportunity to achieve this are the fixer gigs. The game shows a blueprint for an interesting way to present fixers and their gigs with Dex DeShawn. You meet a new fixer, you do some prep work for the main gig, unlock some new game-wide cyberware and some gig-specific tech in the process, meet some new characters and explore interesting new areas.
- Fixer - This approach would allow for more character developlent for the individual fixers, gives the players a chance to meet a new interesting character that you get to know better as you build up to that fixer's main gig - the culmination of a chain of smaller prep gigs.
- Prep work - This is where you put in the existing side-gigs, connecting them with this overarching fixer story and giving them more meaning.
- New cyberware - You could tie some interesting new cyberware (or equipment) as part of the prep work for the gig, similar to how you unlock the kiroshi optics and the ability to see your ammo count in the build-up to meeting Dex. You don't need some abstract concept of Street Cred to reward players for doing your side content. This also gives level/quest designers the opportunity to build the gigs with this new equipment in mind, giving each gig chain its own flavour not just in terms of story, but also gameplay. Think Zelda-lite dungeons, but in the style of Cyberpunk.
- Gig-specific tech - Similar to the spiderbot from the main quest. Gives the opportunity to explore some cool cyberpunk tech that would be too difficult to implement game-wide, but that can inject some unique mechanics into some of these gigs to make them stand out. Doesn't need to happen all the time - don't want to make the quest structure too predictable, now.
- New characters - More T-Bugs, Jackies, Merediths, Royces. Maybe some of them can tie into your lifepath, or it at least gives the team more opportunity to insert lifepath-specific dialog/options with limited scope. Also allows the writers to flesh out the edgerunner world more and gives players some minor characters to connect with, even if it's just for a side-gig or two, rather than the character void that is the current side-gigs collection. it also lets level designers come up with more ways to spice up these levels, given that you will be tackling some of them with a team.
- New areas - Wouldn't it be cool to allow writers/designers to explore the more exotic areas of each of the fixer's city districts for a one-off "main fixer gig" mission that isn't restricted by the main quest structure or what makes sense to be accessible during regular exploration? Yes, yes, it would.
The way I see it, all of this builds on what is already in the game, and also on what The Witcher 3 was doing with monster contracts, and would very much have been able to fit into the game and bolster its design goals.