What? There are competitors out there that will have updated hardware.
Yeah. The new Mac Pro's release date will be determined by the availability of the components they want to use.
Mac Pros are mostly CTO. There isn't any reason to wait just for the heck of it. It's not like they have warehouses of Mac Pros they need to burn through before they release the next model. They just need to switch the production line over.
If it's ready to ship they'll ship it. We're still not there yet, we need Yosemite. But we're pretty close IMHO.