To Paraphrase Ballmer
Applications, applications, applications! Any OS is useless without applications so the key for Fuchsia is can exiting applications run on it without any effort by the developers. If yes, then it has a reasonable chance. If no, then it will be in worse shape than desktop Linux for mass acceptance.
Linux is the cautionary tale here. It has many useful applications that allow users to do almost all the tasks one can do on 'bloat and OS X. But it has a woeful user acceptance rate.