Aside from the issues that have been raised already (which are certainly important to consider), the logistics of designing, developing, and playtesting virtual cards could be a serious obstacle. In particular, I doubt that most people are aware of the amount of time required to playtest new cards (well, to playtest them well, anyway) even under ideal circumstances (multiple groups of players, each with members concentrated in the same local area who are able to get together and playtest in person). The fairly small size of the player base might be problematic, but I think an even bigger issue is how spread out (in a geographic sense) the player base is -- without having people in the same area, it would be difficult if not impossible to manage playtesting. I think it would have to be done via something like GCCG, which would require having the new cards made available to playtesters in GCCG (but not have the cards or games played with them visible to everyone else, unless playtesting is totally open, which has its own set of issues, but might be doable given the non-standard circumstances of this situation).
Again, I'm not saying it's impossible, but I think that dealing with the logistics of playtesting could be a big obstacle to overcome even if everything else (support from Decipher / the Tolkien estate, widespread interest by the player base to have virtual cards, etc) is taken care of.