It should be remembered that the Switch is not even two years old yet so we almost certainly have not yet seen the best it can do graphically. The real showpieces of a system tend to arrive later in its lifespan.
Thats usally more true for hard to understand tools & complex cpu/gpu setups.
Tegra isnt new in that sense (the gpu part, is something programmers understand well by now), and arm isnt a issue either.
I dont think you ll see massive differnces between now, and a few years down the roads, not from Nintendo themselves.
Maybe 3rd party get better at makeing games for it? but I dont think theres that much performance left on the table. Look at panic button, those guys go all out, to squeeze every little drop of performance out of the switch. I doubt theres much more they can do, even a few years down the road, compaired to now. Also devs have been saying the tools for the switch are easy to use.... again going against the sentiment that theres performance left on the table, because devs dont know how to use it.
The same was true with the PS4 & XB1, because they where both x86, and had unified memory pools, and easy to program gpu's,..... things arnt going to get much better than they are now, and how it is now, isnt much differnt from at the start of the gen.
Necro-bump this 2020: http://gamrconnect.vgchartz.com/thread.php?id=229249
Bumb in 2021: http://gamrconnect.vgchartz.com/post.php?id=9047071