You're upgrading for games that don't yet exist, and that's fine but its not an efficient way to upgrade economically, even if you plan to spend a lot.
Lets say you get a $3000 PC tomorrow. It's not really going to be all that much better for gaming than just getting a 4th gen i7 for any games out right now and any games that will come out before PS5. If you get a $3000 PC when PS5 comes out and when games come out that start to actually use more CPU power than a 4770k can deliver, then you will get a better PC in the end just because it will be a few generations newer. "future-proofing" your PC for gaming just means you either spend more or get less. Given that you buy a 4770K and sell your i5 and only spend about $80 in the end to get 95% of the experience a 9900K system would give you for games and then do a big upgrade later and have an even better PC when you actually need it, it seems like the smarter option.
Unless you want to play at 240hz or something, a 9900k is total overkill.
i7 7700kK @4.2ghz
16GB DDR4 3200mhz
GeForce 1080 Ti