They’re free to change the licence of future versions.
Why do you act like I don't know that? The issue here is that once you realize that the license you chose does not reflect your intentions, the damage has likely already been done. From the article I linked:
I didn't have the foresight to see this coming. I didn't think people so lacked in the spirit of open source. I wanted to promote community contributions, not to have them monetized by other people who don't even provide the source to their modifications. I wanted to grow the tools as a community, not have closed source forks of them overtake my own open source versions.