Will the cards be limited to a set/block like MTG? Increasing long term collectible values for earlier sets as well as creating scarcity for older cards? Or will each set/block merge into the last. (for example: Like MTG vs Hearthstone)

Will cards that have been leveled and gained experience remain with those experience points when sold/traded or will they need to be retrained by the new user? In other words will you be able to buy and sell maxed out cards?