USUM has a much taller order than BW2 had to fix their previous game. And BW2 more than passed that bar, it shattered it into a million pieces and gave us things that we didn't even want/expect.
With USUM the bar is:
>Fucking finish Alola, make the entire map explorable, no more teleporting between the entrance and exit of an empty volcano, no more 5 second long routes, actual exploration, an actual victory road
>Reduce the handholding, make cutscenes essential to the (new?) plot only
>Add a proper endgame, with gyms and a complete battle facility like the BF or PWT
Anything else is a bonus. Fail any of these and it'll be shit.