Many do, but many don't. For those that don't, suddenly having the dominant desktop OS turn on them is going to be a big deal.

> And don't some of the same companies store all their company documents, email etc. on Google Apps? Or on Dropbox?

Storing company confidential information on services not controlled by the company is explicitly forbidden at many large corporations. They run their own email servers (not Google Apps), and often ban & block things like Dropbox outright.