Any hardware guys out there? What would you estimate the teraflops to be? The Xbox One X is 6TFLOPs, where would the Navi GPU be on that measurement? Consoles are build differently to PCs and optimization for those consoles goes a long way, but theoretically what would a similar PC build be to the PS5 (I know this is tricky, as Navi isn't even out yet)?

I have a AMD Ryzen 7 2700x and a GTX 1080Ti with 32GB of ram. I'm wondering if I'd need to upgrade to play PS5-era games?

Leaks from some developers that are working the first round of PS5 games say their Sony supplied PC Dev kits have around 20TF. Those are not true console dev kits but mock PC dev kits made to give an early approximation of the real deal. Now Dev kits usually have two of everything plus an overclock. For example the Xbox One X dev kits have around 14TF and 16 cores.

So that would put the actual target specification for the PS5 retail console at between 9 and 10TF based upon the 20TF rumours for the mock development kits. So no you don't need to upgrade from a 1080ti to play games from the next console generation. With superior CPU's and around 10TF they are being made to play, with the usual console optimisations, pretty much all games at 4k 60ps to match the most common TV's now sold, and maybe higher with 120hz free sync TV's coming this year (after all the One X already supports HDMI 2.1, free sync and 120Hz output, so Sony has some catching up to do).
Your PC can pretty much already play any game at 4K 60. The only caveat is that the older tech of your 1080 may lack some of the newer features of the Navi tech, so you may miss out on some special effects that can be handled by Navi at hardware level.

It's too early to really know how Navi would perform.

I'd suspect the targeted TFLOPS would be a bit higher than 9-10 since a die shrink will be involved from the 1X and two 'generational' improvements to GCN as well. The preliminary evidence for 14->'7nm' Vega is around 30% improvement in performance at equivalent efficiency, all other things being equal that gets most of the way to 9 TFLOPS by itself from the 1X's 16nm process. It's also likely that whatever Zen CPU it's attached to will be a lot faster, cooler and less prone to bottlenecks than the bulldozer based jaguar chip- desktop Ryzen1 has ~54% IPC than desktop bulldozer- which should boost performance a fair bit for any game needing a lot of CPU power.

TFLOPS don't mean everything though, otherwise a Vega64 would be faster than a 1080Ti. For practical performance consoles tend to be a generation behind the current top card when they are released, so a 1080Ti ought to be fine. If it isn't there would be little point 'porting' to PC since most people are either on mid range or lower cards or a gen behind.

It's hard to estimate the performance of empty rumors.

IMO, Next Generation consoles based on single chips, will likely have 4-6 Ryzen CPU cores, and 8-10 Teraflop GPU cores.

IOW less than what your PC has.

There is a limit to what can be put into a console aimed at selling for an affordable price.

Though, there are hints of multiple Xbox version in next generation. Microsoft might just build higher end Xbox out of off the shelf components, using separated CPU and GPU parts that are in production.