If you ask me we are going to get the "old Talent tree System From vanilla"
Some Signs that is is gonna happen are these:
1st, in BFA... we got the patch 8.3 that had the Visions Talent tree...
2nd, in Shadowlands we got the Soulbinds... that again are a version of the Talent tree
3rd, in the Patch 9.1 we will get a Torgast Talentree...
4th, Blizzard has been working on Classic Vanilla and Classic The Bruning crusade.... and one of the major things for all classes there are their Talent trees.
5th, when most of the current Devs worked on Classic Vanilla... most of them said that they where kind Shocked how changed World of Warcraft had become from its origin, and if you ask me a part of that is also the Old Talen trees for every spec of every class.
6th, One of the major reasons they changed from the Talent trees to the current was was because the levels... was getting really high... and the talent trees where getting super big... so since they even Moved the levels back to 60 so at this point the talent trees would be way shorter and would work perfectly as in vanilla.
(I am saying Perfectly as getting 1 point each level... not that in vanilla the talent trees where perfect)
So, my Theory is this:
we are going to get a compleat talent tree revamp in the style of the Old talent trees from vanilla... and having a talent system like this on the Classes is an ever green power progression that we would have with us each expansion insted of all of this borrowed power progression system
PS: I know that some of you will say..... but it was a illusion of choice... but everyone will just do the Min/max build... but you would want to pick 0.5% dodge as a skill point in a talent tree...
In a mmorpg... having more chioces is great... and many many people really enjoyed having the talent trees while they leveled up... it gave them the feeling of progression and the feeling of choosing a path and where to take that path each level...
PPS: This is just my theory and something I wish for, not saying its a 100% thing or that Blizzard has to do this... its just a Theory and some wishful thinking ^^
PPPS: And just to make things 100% clear... we could get New Talent trees with the Looks and feels of the old Vanilla Talent trees style.... ofc... we would get a newer version and something way way more balanced and focused on...