Packs will be purchaseable ... people will resale even in the case of Gradual limited $2 packs. The market will raise it to a competitive value probably related to what those cards are valued at for someone who wants to use them in the rental market instead.

Also @yabapmatt and @aggroed have both said they prefer $2 packs... so gradual release is the solution to help not destroy the market. If they decide to go up from $2 that's fine... but I think they can do $2 and let the market decide the value of the cards and leave the difference on the table for their players... that will motivate them to do whatever is needed to get those $2 packs. Play... Stake SPS... get higher in leagues. Talk about a great motivation.