Re: So if I had bought a @tabinnorway
"If you upgrade to Windows 8.5 (or whatever version number they are going to assign it then) you have full support."
You should sue your old school for failing to develop your critical thinking faculties.
If you can upgrade your phone that's fine. But that assumes that your hardware is compatible. That the manufacturer can be bothered to release the upgrade. That the mobile companies can be bothered to test their bloatware and release the modified system (already modded by the handset makers). That the end users knows there's an upgrade, is willing to have all their personalisation and specifics wiped (probably), and even knows how, or cares to upgrade.
Apple have it easy. They aren't supporting many handset variations and they have far more control. But the future of WP will likely be the same as Android - huge fragmentation, cause by the fact that you start "losing handsets" at each step of the assumptions in the paragraph above. For the top line handsets things usually work OK in terms of availability, but once you get to the mid range and cheapies the support effort falls off a cliff when production ends.
So this really does look like a poorly judged move by MS, given their track record and poor take up of WP. It implies they don't care about the owners of handsets they've previously orphaned, and it suggests they haven't learned from Android experience. How much would it have cost them to have declared support available for another few years? The cost of continued bug and security fixes on something that's been released and supported a couple of years would be negligible. Obviously there's a concern that makers and networks might not want to do the same, but MS need to twist these people's arms, and they need to make upgrades far more automatic as well.