From his pinned post on /r/ApolloApp:

Will you build a competitor? Move to one of the existing alternatives?

I've received so many messages of kind people offering to work with me to build a competitor to Reddit, and while I'm very flattered, that's not something I'm interested in doing. I'm a product guy, I like building fun apps for people to use, and I'm just not personally interested in something more managerial.

These last several months have also been incredibly exhausting and mentally draining, I don't have it in me to engage in something so enormous.

I don't think he will. He'll probably avoid investing effort into apps that are reliant on a third-party service now after how he was treated by Reddit.