I don't buy the argument that OSes are as hardware dependent as the OEMs are making it out to be. For example, the BN Nook runs Honeycomb pretty smoothly and it's on some really old hardware.
Hardware doesn't get updated cuz OEMs want you to buy the newest and greatest phone.
My advice is just to wait for the Ice Cream phones cuz the current crop is in a weird transition period like all the phones that came out with 2.1 (What percentage of those got Froyo?)
most of the high end devices that came out with 2.1 recieved 2.2 :incredible,droid x, galaxy s(although it took forever), evo 4g, desire hd, and others.
you are right yes most manufacturers would rather users buy new devices instead of upgrading,
but to the atrix is obsolete, by what standards? it has a dual core Tegra 2 processor has 1gb of ram no other phones have more. So how is it obsolete?
you can argue the thunderbolt is just a vzw evo with lte and you would be right still not obsolete it is older technology yes but still can handle gingerbread since the nexus s is no better spec wise, or the nexus one for that matter.
Hopefully that new google coalition with the manufacturers and carriers is effective soon because then it guarantees updates for 18 months.