Fire OS 3 is why I'll never buy a Fire as my primary tablet. Even though I have a Fire HD 7, I got it and a matching OtterBox case at clearance prices. It was a package deal and is only used for streaming content at work or when visiting family and friends. The Nexus 7.2 is my primary tablet.
Amazon's failure to port Fire OS 3 to the Fire HD is extremely shameful to say the least. It looks like Amazon is operating off the principal of latest OS only for the current generation of Fires (previous gen Fires need not apply). They can learn a lesson from Apple. I got two major upgrades for my iPod touch 4 befopre Apple pulled the plug.
Definitely not pleased with Amazon over this issue