He's not coming back. He clearly says that people shouldn't speculate this stuff. He didn't just stop, he said that he wasn't as interested and keeps saying that he's not gonna start speedcubing again.
However, people don't have to 'move' on, I don't know why people have a problem with this. He doesn't have to still be practicing to be idolized, he was still very great and I'm sure sure he would be if he came back... however, to those who keep speculating that he will come back, don't.
If it happens, it happens. But it probably won't happen. anytime soon.