There's not much to say more than, incredible, and I can't wait. I have got to be honest, for some reason I thought Stardew Valley was all that we'd ever see from ConcernedApe. I'm surprised and delighted that there's more to come! Looks great!
After seeing the news interviews with him, I thought the same. He did seem a little burned out to me after dedicating his entire life to Stardew for so long. Really impressive that he still has the energy to start an entirely new game!
Especially since he has been adding free content to Stardew Valley after its release, also adding online coop (with help from his publisher). I would have expected him to take a long break and enjoy the fruits of his labour, but as a gamer I'm happy to see him back and whatever is creating is a day 1, closed box purchase for me.
I have bought a few games purely out of support for how the developers approach making games. This will be one of them. Open Sewer by Loiste interactive was another one, INFRA was such a unique breath of fresh air that I bought Open Sewer even though it wasn't quite my kind of game.