"Someone's stolen my computer, now I've lost all my data". Oops!
I worked with a startup company and this was one of the scenarios we ran. From this we decided that the business would be 100% cloud-based from the start - a rarity in that sector.
We also decided that "when something's free, you are the product" was a problem for free services. Paying for a "personal" email domain is inexpensive and ensures security so we set that up. We set the whole business up that all files would be stored on the cloud, email would be managed via a secure portal (exchange) which means that all emails can be seen by any device.
When someone gets a new device, we are able to quickly setup the device. If someone leaves, 2 clicks and they can't access anything - this is good when someone leaves under a cloud!