DW said that other Forge liquids are coming. But regardless of the over-exaggeration, this shifts most of mineral resources into the same weird situation as enderpearls: semi-rare and difficult to obtain, until a certain even happens (entering the end or getting the needed book), after which they are limitless and trivial to amass in arbitrary quantities. I am not a game designer or an economist by trade, but looking at enderpearls now, I don't think that kind of progression is good for a balanced game.
It still remains to see how the instability will play into this (and I'm sure this will get tweaked down the line), but the diamond/gold age in dw20's spotlight seemed to be stable enough to harvest indefinitely. Maybe he just got extremely lucky.