If we can't have more decks, why not loadouts?
I suspect that we aren't getting an expansion to more than 15 decks simply because it's heavy on the servers.
However, there is an already half-coded way we can get a loadout system instead that shouldn't be much load on the servers.
What is a loadout?
In this game, it would be a list of deck-names, where if we had an open deck-slot, we could tap a deck-name and tap "Build deck" and it would auto-build the deck assigned to that name in that slot.
If that sounds familiar, it's because that's exactly how Theme Decks work. The Theme Deck system is literally a loadout system. So it is already coded into the game.
So the idea is that we can build a deck and have a button somewhere that says something like "Create Loadout". This would then add the deck-name and its setup details to the loadout list.
Then we can delete the deck to save space, and if we ever want to play it again, we can just leave an open deck slot and go [Decks -> Loadouts -> Tap deckname -> Build deck]... as opposed to rebuilding the entire deck from the ground up.
With each new expansion, the 15 deck limit feels more and more stifling. There are over 50 different decks I'd like to tinker and play around with, but the deck limit sucks all the fun out of the prospect of it.