[hkmurakami]

This is exactly why the "you can buy another great Android device" argument falls face first into the ground for me.

How long can I expect my (at the time) top of the line phone to continue getting the latest OS updates? Additionally, how many (if any) phones get thoroughly tested for OS compatibility and performance for new Android updates? Do I really want to take an unnecessary roll of the dice?

[cheald]

I realize this isn't exactly what you're asking, but most all capable Android devices end up being able to run far-future software via the custom ROM community. My old HTC Sensation (launched May 19, 2011, running Android 2.3) happily runs Android 4.2 thanks to the Android developer community. Even my old underspecced Nexus 1 can run 4.2!

The OTA support may not be there, but that doesn't mean you're hard-stuck with an older version of Android on the device.