Shiny hatch

Yes

It has been verified on the Silph Road reddit, including at least one shortly after the event

I hatched a shiny dratini with a 10km egg I got during the event. Put it into a fast incubator and it hatched 10 min before the event ended. Unfortunately it has bad IVs, but still fun to get a shiny Dragonite. Got two other 10km eggs during the event which I will hatch during the next event. Woulf be fun if the would be another one even though I hope for Bagon, Trapinch or Beldum.