There's precedent where they've done *exactly* that before. They're quite happy to invalidate *months* of work on the player's behalf in order to "improve the game".
I spent 6.5 months building the legendary shortbow...then 2 months later they changed the range on the bow, invalidating it's use as a long-range weapon swap. The character with that bow now has the choice of either not having any long-range attack ability, being absolutely crap at melee, or not wielding the legendary they worked for. *NO* compensation was *ever* made for the time and effort expended and wasted on that.
So that character now gathers dust - between that and AI issues I find it too upsetting and frustrating to play them anymore.
As for the magic-find change...while weapons got to select stats, my magic-find armor set was *pre-set* to a specific stat *without* me getting any choices in it (and not to a stat I wanted to choose, either - it almost duplicated my existing set). They also promised that magic-find armors would become account bound so if you didn't need another extra armor set on the character after magic find had gone you could swap it to another character instead...and *that* didn't happen either. So even there, what they promised and what they delivered were not in keeping with each other.
It's why I've refused to start working on ascended *anything* - I'm sick of having months of work being invalidated and ruined. I'll wait until traits/builds/mechanics settle down more rather than invest time in something now that'll likely be made pointless in the next few updates.
Don't bet on beserker ascended items getting compensated when they change how they works...even if they intend to do so, there's no guarantee that what they promise actually happens...