I can't think of an Android phone that didn't get updates within its first year. In looking at this list:
http://blogs.computerworld.com/16310/android_22_upgrade_list, the phones that AREN'T getting Froyo are old devices (released in 2009), and even MOST of those devices got 2.1 updates, which coming from 1.6 is the equivalent of a Mango update, and those that didn't get 2.1 got 1.5-1.6 updates and bug fixes. There may be some random low end phone that didn't receive a single update or bug fix, I don't know, but I can't find an example.
To compare that with WP7, we haven't gotten ANY updates, and we are only really promised one more (Mango) a year after launch. That seems comparable, except that Android phones actually got the updates and continue to get updates as we speak for newer phones, and we are still waiting. Also, some Android phones have gotten multiple significant updates 1.6-2.1 and then 2.1-2.2, which would be the equivalent of us getting mango and THEN the next big update after that, which again these chassis 1 phones we own have not been guaranteed. Right this moment, the Android situation is unquestionably better, but I do like your optimism.