There's not much PS4 and XB1 have been doing other than graphical improvements though. It's hard to imagine Switch limiting things too much.
Crowds, AI simulation, draw distance, open worlds like TW3 and many other features are not possible last gen. It's not just textures and resolution and framerate.
Look at Red Dead Redemption, towns were like a movie studio backdrop with fairly empty buildings compared to current gen open worlds like TW3 again.
The Last of Us had to cut many combat animations seen in the pre-release footage and female enemies because the PS3 ram couldn't handle that many animations.
Shadow of Mordor's Nemesis system is not possible on PS3/360.
And many other examples.
Even current gen consoles are very limited.
in Dead Rising 4, you can see many zombies on the screen but most of them have no AI until you kill some zombies first. There's a limited number of zombies that can be simulated at a given time while others just stand in the background.
People tend to underestimate the importance of AI and animations.
And those features add a lot to gameplay mechanics and design.