Not necessarily true. Imagine the likes of the Eee PC with a thin client that basically just has Chrome, plus a locally hosted web server with some basic productivity apps? You can run the apps standalone or hosted in the cloud. You could even migrate your local standalone data to the cloud, or sync it so you can work in both modes.

You don't have to move the IE userbase on PCs. It's not even certain that everyone will be using PCs in the future. (Maybe just content creators, designers, and programmers will be using them?)