Without wanting to read too much into the circle cut, it does give you ideas. Like with Sumireko being from the present and Renko being somehow related from the future, and the Lunar Orb further being connected to that. The titular Ultramarine Orb (is that the same thing as the Lunar Orb?) allowing one to remember any detail from the past. Yukari's moon excursion through gaps in Silent Sinner in Blue. Kaguya having time control abilities. The Pointdevice mode allowing you to peek into the future.
There's a bunch of loose ends about time travel, but not enough for me to speculate. I mean, ZUN tends to improvise and bounce around with the settings, but this time around there's really the feeling of a story arc that even shows up through his sketches.
(Uh, or it's just ZUN's way of saying "here's to Touhou continuing into the foreseeable future".)