This is not implemented yet, but once beta arrives cards in your collection will be locked to specific games. Once that colony is abandoned / fails you will then regain access to your cards which were used.

Inside that game, each card will generate a game asset. This game asset can be sold/traded in the game market or destroyed. To my understanding this game asset is not an NFT and is unusable outside of exode. (with the exception of Exofuel which is a currency token)

There are only two ways to permanently lose cards

1. Choose to burn a copy to upgrade another copy of the card
2. Burn a card with the "droppable" keyword to instantly send it to a colony you currently are playing.

Hope that helps. Its not one of my better explanations!