I guess the advantage of this setup, relative to playing a board game on an iPad, is that keeping info hidden from your opponent is more natural with cards. I suggest to exploit this, you either make the cards thin enough to hold in a hidden 'hand' the way someone might do in magic the gathering, or (much easier) have your plinth include a hidden hand prop section ala Scrabble.

In terms of product development, I think the best path would probably be to create or find an opensource game engine for cardgames and have a nice development environment plus API where a dev can write a game for the engine that either runs on a PC or runs on the cards, with no code changes required. (PC support makes debugging and iterating on game design much faster.)