One privacy advantage of Wire is that it does not force you to upload your address book to their server.
Maybe being open source will change that, but I can't see it being a significant factor for the hundreds of millions of users they need to even begin to catch up. I think they were betting on end to end encryption to save them, but their biggest competitor launched better end to end encryption by default before they could.
You're right, they sold Skype twice, so they're not stupid. They're unlikely to keep throwing money away when the writing on the wall is this clear, and word on the street is that they're looking for an exit.