Don't mix PC industry with mobile industry. It's not the same, not even close. The way things are marketed and distributed are very different. I don't thik that anyone here uses 10 years old mobile.
And for the rest, thats why I said that it all depends on how the company is willing to treat there own products and there own customers. It's up to them to decide if the want "I'll screw U once" approach or if they want customers that will come for more.
And I sad 2 years because it's the most common contract length and then everybody signs a new one and buy a new phone. And 2 years of propper support would be something that we still haven't seen from any manufacturer (well, maybe Apple. I don't know exactly what was the latest update original iPhone got and how many of "new" features it got with it). Every other simply pretends that the cetrain device never existed after 6 months or so. Also it's worth noticing that carriers are also guilty for that, maybe even more than manufacturers but still..........I was screwed with P990, then with satio, then with N900.......... So yes, if I get a propper support for only 2 years I'm all in.

It's impossible to have a fully open OS and to be a manufacturer at the same time and to be something on the market. Sooner or later someone will just take that and put it on some cheeper HW and that's the end.
OK, google created "open" OS but the reason for that is not to please users or manufactures but as a tool for selling adds through their services. I'm not interested in that. And I'm also not interested in gazzilion cheep craplets and mobiles from this year which are inferior to my N900 but they does exist because they can use google's OS for free.