Kind of cross-posting from the other thread about the tweet. I just finished it. Loved it.
I think it'll be a while before we see anything more of it. He said it's been three years just to make this first chapter and he hasn't done anything more or even started to build a team, so we'll be waiting a bit.
But Toby is an extremely talented individual and I have zero doubt that he'll find a way to make the thing he wants to make. I'm sure there will be no shortage of similarly talented people lining up to help him.
His quote about not thinking he has the ability to make something that will make people feel like Undertale did is interesting. And honestly I disagree with him, because the things that I enjoyed most about Undertale weren't the subversions or the multiple endings or the twisted nature of it. It was the pure charm of the characters and the writing, and I think Chapter 1 here already shows that he is capable of creating more of that.
I do agree with some of his misgivings about the battle system. I think because the game won't change whether you are pacifist or genocide, there needs to be equal incentive to do both. Pacifist explicitly makes the game tougher by preventing you from gaining XP and there really isn't a benefit other than narrative, which is one that won't exist here. And I think his thought about the battle system not totally working with multiple characters is a concern I share. I think there should be some sort of change in how you defend when multiple characters are targeted with one attack. As it stands now, you defend just the same, the only difference being multiple characters take damage if you mess up. And he is right that any sort of pacifism against stronger enemies is a lot of defending with the characters you can't Act with.
But as I said, I have no doubt that he'll figure that stuff out and put out a great product. And I'm fine waiting however long that takes.