Matt Makes Games has been...making games for some time and if TowerFall put the developer on the map, then Celeste claimed an entire continent in its name.
It's been taking the indie (and Switch) scene by storm this year (expect to see it in plenty of GOTY roundups) and there might be more of it on the way. Simply teasing it as a "work in progress," MMG boss Matt Thorson tweeted out a small multi-screen level that seems like it could either be the basis for extra challenge levels for Celeste or a level editor.
As a Twitter user in the thread points out there's already an unofficial map editor, but that's only on PC. A free update that adds a full-on map creation system into every version would be something else. For now it's just speculation.