Actually I didn't saw such problem since a long, long time ago, when there was aim problems in games using both perspectives, and I suppose in lazy FPP games there is probably animation problems if translated to TPP (but C2077 doesn't look like a lazy game), but aside of that I see nothing.
That's why I'm asking about precise exemples of what could be such things that have to be redone to switch perspective.
Im saying in terms of how the game is built.
Well, animations for both would need to be top-tier. You could argue that 2077's FPP animations so far are... lacklustre, of course, and I'd probably agree (they are smooth enough, but there's not enough animation for interacting with the environment). But theoretically, in a game that aims to do both perspectives justice, it would be an expensive and time consuming process. And not sure if it would be worth it. I imagine a lot of people that claim to hate FPP will buy the game anyway. Not all, surely, but the remainder might not generate enough in sales.
And, of course, in this case, there's the difficulties associated with adapting the Interactive Scene System into TPP, and the player being able to see things via TPP they wouldn't in FPP (thus making it more difficult to set up things like ambushes, surprise car attacks, etc).
Can you design a game like 2077 with both perspectives in mind? Surely, yes. But at this stage in development, or even at last year's stage in development, I highly doubt it would be as simple as adding an optional mode, despite what many people believe.
To be fair, we actually don't have any evidence that they are smaller parts of the game. In fact, if CDPR keeps to their word by allowing players to usually have multiple paths through a mission (some of which/many of which may even be nov-violent), I'd argue that shooting may just be a very small part of some people's games. Which is not to say it will never happen. But it would not surprise me if I could spend most of my time talking, exploring, sneaking, hacking, and engineering and a smaller part going all shooty shooty bang-bang.
I'd hoping for pure stealth/passive options to be a major part of the game. Generally stealth is the easier route, but personally I think it should be more difficult but more rewarding. Full blown shooter aspect should be the easier approach as its fairly straight forward and wont take much to blow through an area, probably.