It's 100% the engine. It very poorly utilises GCN, as anyone with a Polaris or Vega card can attest to. It's even worse in Wildlands/Breakpoint (same engine), though at least in the latter they gave it Vulkan and that helped out a bit. Once they make the jump to being fully on next-gen only you should absolutely see a very different type of AC (visually). This one's just gonna be Odyssey 2.0, same jump as that did from Origins (i.e. not much at all).
Mind you, they might still not push 60 fps in the future. Native 4K or ray tracing for that sort of an open world game is simply going to be very taxing. So it's either those kind of better visuals at 30 fps OR some reconstructed 4K like what Massive's doing with great success in The Division 2.
I wouldn't expect to see any radical departures for games before 2022 though. These things just take a long time to make & there's always market considerations butting in as well.
Mind you, they might still not push 60 fps in the future. Native 4K or ray tracing for that sort of an open world game is simply going to be very taxing. So it's either those kind of better visuals at 30 fps OR some reconstructed 4K like what Massive's doing with great success in The Division 2.
I wouldn't expect to see any radical departures for games before 2022 though. These things just take a long time to make & there's always market considerations butting in as well.