Are you seriously trying to claim Office 2013 in Windows 8 is radically different? And that its not that much different than Linux and something like LibreOffice on KDE/Gnome?
They'll lose more than 300 in dealing with interoperability with the rest of the world alone trying to exchange documents, let alone the training.
Metro is a branch of applications, not the entire OS.
You are so ridiculously uninformed about Windows you can not possibly comment on what migration would be like based on the silliness of your post.
Pretending they'll save money on the migration is just ignorant. If you want to argue that in 15 years, they'll save money, you MIGHT have an argument, IF you ignore the cost of shitty interoperability, but only if you ignore that. You have to have a pretty narrow view of the world to think they'll actually save money.