I mean lots of things can happen if you let your imagination loose. The way you're talking makes it sound like it's set in stone that by a certain point in future, Japan is confirmed to become America 2.0 electric bogaloo.
These "LGBT laws passed in Japan" are a bunch of nothingburgers that don't matter. Gay marriage is still not legal in Japan. LDP will continue being in power for a gazillion years because the old people are teaching their offspring to vote LDP. And there is also the Unification Church. The article 9, the single most important debate in Japan, will eventually be abolished whether anyone likes it or not. Japan is to US what a man is to a whorehouse. US needs to store its weapons in Japan, not the other way around. If the next day Japan says they are officially making it illegal to support the LGBT, US Gov will stay silent on this matter. It doesn't matter if Joe Biden says trans rights or some random military guy comes out as gay furry because the actual important people making the decisions are not dressed up in furry suits despite what the media tells you.
Even if we disregard all of that, you cannot change the nature of a population that is a continent away from you unless you start mass importation of said people, like the UK or France. And that is going to happen in the next never.
Consequently, the "Japan has fallen" narrative is false, and US right wingers blabbering about it won't help Japan. The only thing that will help Japan is racism, LDP and God.