Legendary raids - Temporary or Permanent?

Is this something that is temporarily happening as part of Pokemon Go Fest ?
Or Lugia and Articuno are permanently in the game now, in some form ?

I think they are here to stay. There will probably be less of them though…

I hope you are right @JoshHack!

I agree with @JoshHack I think we will still see them after tomorrow but in much lower rates.