The final build number could somewhere be around in the realms of 7xxx, since from Vista development days, the build numbers were determined by feature branches and not by daily builds. So they might not deviate the build number very much from the winmain branch, which was 7000 for the 'feature-complete Beta".
Then,
Another possibility is, they might set the build number artificially, if they desire, to something cool...may be like 7777.