Legally speaking, the card name and lore of existing cards needs to remain the same if we change tem. That way we're not making new cards but clarifying existing cards to be used in current gameplay.
Making completely new cards is a lot more complicated because then we're going to use their templates even if we use our own images.
But to start with creating virtual versions of now out of play cards is a good start to revitalize the game. Imho it has the following advantages:
1) Old cards are still available to the players who left after
Mount Doom so altering them to the new gameplay might draw them back in.
2) Virtual cards can be done without artwork. Just the new gametekst in a corresponding template of the lower half of the card. Leave lore, name etc in tact to avoid problems with the big D.
3) Can also be used effectively to create erratas for broken cards that are in current play.
I suggest that we do this first and wait with the creating completely new cards. This btw doesn't mean that we can't introduce new game mechanics as long as we use new card texts on existing cards.