I'd like to see advancement as hand size and allowing selection of cards from certain categories. I'd like to see standardized cards.
So, for instance, if you were a level 5 wizard, you could use level 5 wizard cards, and if your total level was 10 you could use maybe 8 cards (5 standard + 1/3 levels?). High level characters may be allowed to create multiple draw decks?
This could allow for fun both for a manufacturer but also for players; I can see using something like Roll20 as a playing method for "free" games, and digital deck emulation software shouldn't be difficult to find. If you don't have art-intensive cards and you just have rules, you could even print out a deck cheaply. You could even write by hand, and if you're not a stickler for competition-grade anti-cheating you could just do it on torn up paper.
EDIT: I'd address Decksible more closely, but I really don't understand it.