I get the feeling that tank damage will likely depend on STR and VIT, maybe a 70/30 or 60/40 split favoring STR. This way you'd still do more damage in full STR, but the gap wouldn't be so wide with VIT contributing to damage as well. Possibly they'll go with something more complicated (like one stat being a multiplier of the other or something) or just base all tank damage on VIT and remove STR.