I'm not sure I want a sequel to Shin. I like where the movie ended, but more than that I think Shin had a very distinct purpose that it fulfilled within its runtime. Pumping out sequels with more monsters seems pointless to me and ignores the integrity of the film. And on top of that, Hideaki Anno himself said he has no plans to return to Godzilla.

By all means, keep making Godzilla movies. The next one should just be in its own universe. (Which seems to be the case with the anime Godzilla film coming out later this year)