Network-based audio playback is definitely the future as it is for multimedia in general. Just as there has been an explosion of manufacturers jumping into the DAC business, more network players are right around the corner.
If you're using your PC or MAC as a DAC or digital source hardwired to a DAC then sure you can argue all day and night about the pros/cons of USB, firewire or any other physical interface, quality of PSU's, fan noise or whatever. But if you're streaming your music over wifi (not bluetooth in its current state) then it won't take long for those variables to be made irrelevant by the very nature of how networked computers work - hardware and software layer abstraction.
So long as your network is up to par, a $200 chromebook will feed your networked DAC the same file as a $2,000 gaming rig. And home based networks have been more than capable of doing this for a long time with minimal router tweaking by users.
Additionally, you can't talk about computer based audio in terms of quality without admitting that in terms for, DISCOVERY, computer-based audio is already unparalleled and getting even better.
For the record, I've been building gaming PC's from scratch for years. All the music I buy nowadays is vinyl (new or used) and I use Rdio extensively.