Not below 90 .
First reasons is : 7 EXTENSIONS , there too much thing existing to go back to 60 .
It works when game was news , but not now
But … What if instead take your level, they add news rows with damage increase / cooldown reduced between each major ? Like .
Each 5 level you can choice one minor talent to upgrade one of your existing spell, then each 15 you get one major point who allow a powerfull spell/gamechanging passive .
And two news rows with one being 3 différent “legiondary” (no seriously, who think it will be fun to add them at your regular row when they are not enough interesting) And second being “Azerith” with 3 of the most popular for each specs to allow player not feeling too week when you lost them totaly
It will be a mix between old talent tree/ news with more choice and more fun.
NB: If they want you to feel more powerfull when you ding, STOP taking away what you get and give you news thing instead.
Being low level again wont make me happy if i lose again something who make me fun to play everytime .