Doubt they will go free to play, but they really should really do away with buying the old expansions to progress. Should just buy MoP and get everything.
For a new player, it's a gate. Have to buy base, BC, LK, Cata, and MoP to get everything. I know there is a pack for base/BC/LK, but still your asking a new players to drop $80, and a monthly fee to start an almost 9 year old game, when they can spend $50-60 on a new game.