I believe the game would attract a larger player base if it were on Steam.
A Steam version or a standalone version would also probably allow you to implement some nice features like: better animations, fuller player profiles, avatars, in-game tournaments, campaign mode, cosmetics, etc.
Seeing as Dominion is one of the most popular card/board games, I think there would be a market for a Steam version, and potentially some pretty good money to be made! The art assets are already completed, so it would be a matter of adapting what you have and expanding upon it. Myself and a few friends would be very happy to spend a lot buying a Steam version.
Thanks for considering.