So, here is my take on the future PrE's/races/classes that I can see coming out.
1. House X Dragonmark Heir will be unlocked by unlocking top tiers of favour in the relevant house (cool reward idea!).
2. Some of the future racial PrE's will be premium.
3. Completing every quest in the game on elite (maybe epic as well) will unlock Feats and a PrE associated with the Dragonmark of Death (yeah yeah? Maybe feats for everything on elite, PrE for everything on available on epic)
4. Gnome will be a free race (I hope, don't want the balance of f2p vs p2p to go too out of whack).
5. Druid will be p2p
6. Some other races will be p2p (shifter race right?)