A FET2, with all new characters with FET1 as a lore but MC starting with all powers... Even a hint of this would allow a more open ending without being unsatisfying, as long as it does not go like Akabur's Princess Trainer (that last I heard he said would never be continued).
I'll be honest, great idea, but VERY open too. You can do... about anything in there if you have a good story. That is good but also bad. Mity did great under the confines of the canon Avatar, but we can't tell how a brand new one would go. There is a reason so many fanfics seem to have god writers but go down in quality after breaking from the canon railroads (if they don't go out of their way to stay in them).
After all, for every Mad Max Fury Road there is a Star Wars Sequel Trilogy.
Makes me want to ask Mity permission to make my own version of FET2 later if they don't want to. Or as a gaiden story.
Of course, I'd need to know the actual background story/problem/current ending first, so I can only make minor plans until the epilogue (don't really want to ask how it would go and spoil myself if they answer)