2. Dual wield with at least one 2-hander.
3. More/better fury generation (or reduced cost for spenders)
4. Improvements to fury spenders (via synergy, legendary effects, or straight buffs)
Edit: 2.1 review Aug 19 -
1. Perma WotB is almost a possibility, but not achievable with max CDR gear + Gogok of Swiftness (20.5s cooldown). Three new items bumped the max CDR for Barbs from 65.9% to 77.2% (if I calc'd correctly) - Leoric's Crown, Gogok of Swiftness, and Vigilante Belt. None of those were WotB specific.
Further, even this sub-permanent cooldown level is impractical because it requires several 8 & 10% CDR affixes in slots you don't want to do that in (Amulet, Capt Crimson's Set, Vigilante Belt, rings [where now CDR competes with mandatory sockets as well]).
2. We can't dual wield with a 2 handed weapon. The 2-hander readjustment addressed this nicely for me, though. That said, I've wondered if applying a Heavenly Strength-like penalty to a Barb passive that allowed them to DW 2-handers would work.
3. Earthen Might is back - good. Primary skills generate something like 12% more fury in some cases - not so useful. Ancient's Fury generates 33% more fury - not bad. Mighty Weapons generate 100% more fury via Weapons Master - bad.
Overall this has largely been unaddressed. The best fury generation we had prior to 2.1 was snappshotted Ancients, and what we're left with doesn't match up well with that.
4. Major disappointment. The biggest buffs to spenders so far have come from the 2h buff and legendary gems - not from barb-specific legendary affixes and certainly not from base buffs to the skills themselves.
New items: Lamentation (Rend belt), Remorseless (HotA spawns extra Ancients) Vile Ward (Furious Charge damage increase for each enemy hit).
Vile Ward is completely friggin off-the-charts powerful, but the only relationship it has with spenders is that it discourages them further. Remorseless and Lamentation don't make their buffed skills build-defining. Remorseless beig season only means we haven't gotten to play with much it yet, but the early returns are that it's a lame gimmick. Rend needs more than Lamentation is giving it.
Fury of the Vanished Peak (half cost SS) is good now because of the 2-hander buff and the new SS +%dmg affix.