Dump them now: All D3V commodities and gems. All weapons.
Easily upgraded in RoS: Boots, belts,
shoulders, bracers, chest armor, most helms, shields, orbs, mojos, quivers.
Top quality D3V still viable in RoS: Rings, amulets,
gloves, Mempo of Twilight.
The most obvious change is the completely worthless nature of every Diablo 3 commodity in Reaper of Souls. All gems, plus Tomes of Secret, Demonic Essences, and everything else you get from salvaging is virtually worthless in RoS. If you want to bet that the game stays much the same at release as it is now, you should sell all of your gems and materials at once,
while they still hold value. (Gold is useful in RoS, though much less all powerful than in D3.)