I secretly hope the campaign will have a overworld map (like the one in Puzzle Quest) with towns, contacts, side quests, story quests, choice and consequence.
If they manage to pull this off, Gwent would easily kick Hearthstones sore butt.
I think it will be overworld map cause it would be really tough to make 10+ hours campaign otherwise. I heard in campaign you will have your own army (your cards are your army) so probably it will be conquest of some sort.
HS story mode is BS I'm sure Gwent's will be much more better.