I just see no incentives to play Prot. At all. We're not too squishy(so being tankier does not mean much) and you actually lose utility playing Prot(you lose Rallying Cry). Sure, you trade MS for a dispel which could be really strong... But you will do less damage than Arms or Fury(you will cleave better than Fury but not Arms). And you lose out on one of the things that makes warriors good atm(a really, really powerful execute).
I'd like Gladstance/Prot to be a thing. As it is really fun and smooth to play.. But I don't think doing a good bit less damage and losing utility for a dispel(and being tankier) will mean much. Maybe I am wrong...maybe trading that extra damage from Gladstance and picking up AM will make it similar to what it was at before Gladstance lost the dispel(viability wise). But I still think it is behind Arms/Fury.
Gforce went almost 2.4 with prot stance recently if I'm not mistaken.
Now with these buffs that improve directly prot stance dmg, well, dunno, figure out yourself.
With right comp prot can be glad viable imo now, maybe ATC or some variation of it.