I recently picked up legends of runeterra, and ended up not playing the actual pvp part of the game at all. It's a sort of roguelike PVE game unto itself that has really compelling (if a little grindy) meta progression where you unlock new characters which have their own unique decks and then you level the decks and the characters up by playing the mode.
I think Gwent could do something along those lines, you already have a bunch of established archetypes that could be connected to different established characters, (e.g. Eithné could be a symbiosis deck, Eredin could be a frost deck, etc.) and I think Thronebreaker is a proof that CDPR could definitely make compelling PVE encounters.
Going to different regions in the witcher universe with unique encounters in this kind of roguelike gamemode would be a super exciting addition to Gwent, IMO.
Source: https://www.reddit.com/r/gwent/comments/18dcww5/do_you_guys_think_gwent_would_benefit_from_a/