What they need to do is apply those techniques that they did on Switch to the PS4 version and it will look the best. If it looks good on Switch it cannot look worse on the more powerful PS4.
Unfortunately they truth is that at this point, there is no incentive for studios to pay devs to apply those techniques now that sales of the game on PS4 are pretty much done.
At this point the only hope left is for a remaster of the game on PS4. Who knows, one can dream 







