Lock-in might be OP if they leave Warhammer as a Hand and a Half like Bastard Sword via SWF+THF monk to take advantage of all the new buffs in a single build. "Real" THF builds are unlikely to threaten raid metas.
I have 4x raid chars (ranged, melee, tank/melee, tank/caster). The patch will be a huge buff to my melee (it's a monk) as-is; more with slight gear update. Tanks will be fine, slight gear fixing req'd only for caster. Ranged will need a full TR rebuild into a different style (I'm hoping simple thrower will become viable, but it's looking like Bow+Monk).
I have a suspicion that in general, nearly all ranged will need a full from scratch remake. Casters might squeak by with a full Fred'ing. End-game raid melee will need to remake (likely monk rather than DL/VKF). Tanks crunch popcorn and cheer the chaos.
Some kind of freebie to help rebuilding would be nice: Free Freds, LR+X hearts, etc., but while I hope they'll do that, I'm not hopeful of it. Fred is much more likely than LR+X hearts.