Apple updated its support document for Boot Camp that now shows the 2013 Mac Pro as only supporting Windows 8. It’s an interesting move given that Windows 8 has not exactly been embraced in the marketplace. Windows 7 seems to be the one everyone on the PC side has decided to settle down with. Then again Apple is not one to hold on to old operating systems for long – they did have a literal funeral for OS 9 after all. And it’s also not Apple’s responsibility to shield users from Microsoft’s mistakes. But one should at this point assume that Windows 8 will be the only option for any new Mac models.
It should be noted that if you do need to run Windows 7 you can always A) run it on an older machine, B) run it on a machine that used to be supported (generally an existing Boot Camp install can continue to run even after support has been removed – generally), and C) use virtual machines such as Parallels and VMware, which will continue to support Windows 7, and Vista, and XP, and 98, etc. At this point virtualization is good enough that it’s almost always the better option anyway. Unless you are a gamer. For normal tasks, save yourself the reboot.