Google Hangouts is nice, but most/all of my clients use Skype and cant be bothered to switch. So while in theory not a big deal, in practice it kind of is. Even running Skype in a Linux enviroment is kind of a pain im afraid.
While the ubiquity of Skype is nice, I remember a time when people used other things. That might change someday as well. Either way, that's out of Google's hands, it's up to MS.
I've always found getting Skype running on Linux to be easy though (Ubuntu, Fedora, SUSE, Arch are all trivial)...
