why are is everyone coming to the conclusion that this is like F.G.T? Because from what i read in the chapter, it never gave any indication of it being a final form. Like i read in another post, it seems unlikely that Kirbie would use it so willy-nilly if it was a final form, and if he was in danger of losing his powers. This transformation seems significantly more controlled, and for me the glove seems to suggest that they can go in and out of the Holy Form at will.
The thing is, if we assume that this form is the equivalent of F.G.T and the Quincy could lose their powers after using it, well then that means all the people with the ability to use this technique, will lose their powers after using it, which seems retarded if you will be waging a war. That means for every soldier that encounters someone they cannot beat using their normal quincy powers, they gain godly powers but that takes them both out of the war(provided the shinigami is beaten). It seem to be too unreliable a way to wage a war. And from what we have seen from the Emperor, its not his style to be unsure about shit(the little we've seen).
Its actually more apt to compare it to bankai, however weaker or stronger it is than bankai. If we are making comparisons to Uryuu's form and Kirbie's form, it could very well be that, Uryuu's was also of the same variety but maybe because he wasn't ready for the sudden burst in energy his body couldn't handle it and he lost his powers. I feel that maybe that was what happened to Ichigo as well(maybe).