I am sure they are still popular, but I do remember seeing a time when practically every kid was walking around with a box full of trading cards, and I don't see that anymore.
I think these digital versions, with Splinterlands and now Gods Unchanined, will help further drive blockchain adoption.
I believe Gods Unchained is both an Ethereum and Steem game. Not sure but I thought I saw Steem Prize giveaways from Gods unchained. Super interesting times right now for Steem blockchain.