Stardew Valley creator Eric "ConcernedApe" Barone has said that while there "isn't currently" a Stardew Valley 2, he "would not be surprised" if we eventually got a sequel.
While he wouldn't be drawn on his upcoming plans, Barone said that while he was unwilling "to commit" to Stardew Valley 1.6 - which isn't a surprise, given 1.5 is still in development - he wouldn't be surprised if there was "another Stardew Valley update, or multiple updates, or a Stardew Valley 2".
"I'm not willing to commit to Stardew Valley 1.6," Barone recently told Game Informer (thanks, Comic Book). "I will say that I definitely love Stardew Valley. I love it as a world and a universe. I don't think [1.5] will be the end of Stardew Valley. I would not be surprised if there's another Stardew Valley update, or multiple updates, or a Stardew Valley 2. Who knows?