Is this just your opinion or has Sel actually said this?
It's an informed opinion shared by a lot of people here.
1) His stated plan of three "routes" (more accurately "phases"), with us being in the first phase presently.
2) About a year ago, he said we were about %25 through, so we're approaching the %33 mark, or about the time when a phase shift would logically occur.
3) The stakes are rising. We have a god speaking through Yasu, demanding certain actions be performed before the coming of Winter with nebulous consequences, we have the most recent reset starting in a blood-filled room with a corner of what appears to be Yumi's PJs visible from behind the couch (implying she's been killed), we have the recent discussion of psycho Ami in-game, and Ami's overall behavior. This all points to us approaching a cliff-edge.
4) As each chapter so far has focused on a single season, and each season has spanned two resets, the logical conclusion is that the next reset will push us into Winter, and Chapter 4. A chapter break would be the optimal time to also shift into a new phase.
5) The only reasonable out would be the arrival of Autumn, something that has been stated to not exist in Kumon-Mi, but it's also been said that things are changing. This would give us another year of build up, potentially, before the shift.