IMO, kotlin makes a much better candidate to be "the" cross platform language for server / client since it supports typescript as a first class citizen, and a native target is coming.

You could use the same arguments in the article you posted to posit that everyone will be developing on a Mac.

It's not very convincing to me.

It doesn't seem to be particularly relevant; potential for server-side usage of Swift is one thing, but Swift apps for Android devices have quite different challenges and reasons for (non)adoption.