This is definitely an interesting announcement. I'm happy that they are offering free upgrades to all users 7.1 and up. I believe this is a really smart move.
Wow this is a serious game changer, I was thinking about this the other day. I would be great to be able to turn off and on a sim card in your smartphone. So if you were using an iPhone and wanted to use your Android phone you just turned the iPhone sim off and used your android phone without having to call and de-activate it everytime.