Note: the title is missing "unless the open source model evolves".
I wonder what that would look like. Perhaps it’s time. But the grey area is just so vast.
It’s nice for self hosters perhaps. But I for one am always thinking about how I can commercialize my self hosting skills (and have been somewhat successful here and there).
What I do wish is that all companies who have this kind of license would also have a clearly priced, clearly defined "pay us X and you can use the OSS bits under this commercial license instead" model, for exactly the reason you describe though.
If they’re paying for a service because they need it (not so they can resell or repackage it in some way), I don’t think they’re going to be so picky about the license. They pay for plenty of 100% closed and proprietary software after all. The benefit of OSS/SA licenses in that case is debugging, being able to contribute patches, and continuity if the vendor goes bust. For those purposes, having access to the source is what matters, not the particular license.