Even then, for the "everyone who already uses Linux/BSD/etc.", I would posit that most of them are probably using Macs and/or aren't waiting for "The Linux Desktop" to arrive.

For a huge swath of *nix users, Mac OSX accomplished everything they wanted from a "Linux Desktop" outside of being free and open source. That probably leaves a very small number waiting for the Linux Desktop.

FWIW, OSX is also unified, and requires little knowledge of the plumbing for end users.