Well, I'm sure you won't need a next-gen console, with the exhaustive list of X1X and PS4P games that look better than Returnal, while also running at 60fps.
Maybe you miss my point, as you refer to 30fps current gen games running at 60fps on next-gen consoles. They didn't run at 60fps on current gen machines right? So that means you can't find anything on the current gen at 60fps, that looks better than Returnal. I'm not a master linguist, but by definition, that should make Returnal's visuals next-gen, as they exceed what was possible on the current gen. Unless there exists some imaginary intermediate state between current gen and next gen, where a game like Returnal resides visually. Schrodinger's gen, I guess.
This silly semantic trick is some bizarre dance that gamers have seemingly invented to cope with the ever-shrinking bumps in graphical fidelity with each new generation of consoles. But the simple definition used in the past should still apply today. If it wasn't possible on the existing consoles, then it resides in the realm of the new consoles.; ergo, next gen.