But Steve good Sir...
Not wanting to keep flogging the dead horse too much, WHY does the Nexus One fit into this, as the only factor that applies to that, is that it's not being 'made anymore'.
Fitting your other necessary criteria, not only is it still being SOLD (Voda, other European operators etc), it is yet to even receive (any second now though/ongoing), it's 2.2 Firmware.
So how can it be obsolete, when it is still being sold...
...still to receive 2.2...?
...And given the recent Google announcements regarding the hardware spec for Android 3.0 being RECOMMENDATION only (notwithstanding the Nexus One meets it anyhow), it will likely see 3.0 come Christmas/early JANUARY 2011...
Why does that fit the mantra of Obsolete even using your own definitions mate? lol.
It is a phone still being sold (admittedly whilst current stocks allow).
It is about to get a new Firmware update.
It will see ongoing Device Support for some time.
It will likely see a new firmware again, come 3.0, possibly even into 2011.
That's probably where and why your definition of 'obsolete' falls down, if only applied to meaning a phone still being manufactured, and hence your good reason for floating this whole topic of course, so well done in that sense.
The bogey here of course being Nokia, where they thankfully DO choose to issue FW updates for old devices now and then, BUT not having any clear strategy or assurance that this will happen - it's very pot luck.
Whereas for the Nexus One, policy is rather different, in that the world and his dog can bet on the N1 getting Android 3.0
GREAT article though - very thought provoking for sure.
(Mine's a Desire, as it happens, so I'm just playing Devil's Advocate to be fair to N1 owners, as my Desire does not fit the EOL mantra, still being made for now).