One adaption is his ability to absorb other life forms, his tail is the first evidence of this showing what appear to be other sea life.
going forward, they can fight us on more of an individual basis, one to one, where Godzilla can't, and allow Godzilla to continue to evolve even further. It's sort how we out lived the dinosaurs, we evolved to adapt better then they did. Godzilla maybe realize bigger isn't nessacarily better or that he needs to be more able to fight us.
Godzilla could be essentially making himself into a "God" like figure to his followers the human/Godzilla hybrids, "The Children Of Godzilla", his own race so to speak, what more perfect evolution could there be. We will just have to wait for the potential sequel to find out.
Note: photos in this article are from variest Facebook pages.