I don't think source-available licenses have any chance of outcompeting open source, or at least I hope developers won't let them.

Open source thrives on contributions. The moment you restrict what I can do with the software I'm supposed to contribute to is the moment I ask myself: "am I being asked to work for free, solely for the benefit of someone else?".

The incentive to contribute completely disappears (at least to me) when I'm asked to do it for a project which "belongs to someone in particular".