Yessss. I don't use Mypaint or Blender though, I find that anything I could do in Mypaint I can just as easily do in Krita, and I'm not really into 3d that much.
But really, I don't see any need for photoshop, except for a very few niche applications that still can't be done with free software (I think there was some stuff having to do with photography and raw processing, but I'm not sure). Krita also saves in PSD now, so that's one less roadblock for linux artists.
Krita's brush system really is awesome, there just isn't anything comparable. I only wish they'd remove that damn sketch brush, because it keeps me from doing anything productive, wasting all my time just playing with the endless possibilities of it....
Mypaint has infinite canvas and the ability to limit the gamut of your colour palete which Krita doesn't currently have. I would say Painter has a comparable brush system - Krita has some brush engines that Painter doesn't and vice versa. I think that krita has better workflow than the most recent version of painter I owned (8) and I suspect that is true of the current version. Krita has hands down the best fullscreen paint mode I have come accross to date.