Not sure if this has been discussed or suggested. I couldn't find it on a search (I did give a rather weak effort though).
I really have enjoyed some of the mini-games (notably collectable card games) that are found within some of the titles I've played.
Examples: Pazaak from KotOR, Gwent from Witcher III, Triple Triad from Final Fantasy VII
Would anyone else be interested in a similar experience in an MMO like Pantheon?
My gut would say the best experience would be a simple but competetive CCG style game that is a separate experience from the game (ie in no way does it impact items, questing, or power levels), but only for the collection and competition. The impact to the MMO experience for those that don't partake shouldn't go any further than economy (supply & demand). Of course it would be a unique game and somehow fit into the lore and theme of the game, but I do think it would be very cool.