And I still trust them less than I would somebody with profit motive. There is no reason to assume that the Nook HD+ is still going to be supported in 2017. There is every reason to believe the Surface RT will be.
Well your distrust is unfounded and unlike you, I have provided you with many many examples of large community support for devices continuing well after the manufacturer has dropped support.
http://forum.xda-developers.com/nexus-one/development
Multiple projects are working on getting Kitkat running on the Nexus One. This phone is just over four years old and Google stopped providing software updates for it in late 2011.
The story is very similar for many other devices.
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And I still trust them less than I would somebody with profit motive.
Ongoing support costs money and that eats into profits. I trust a corporation to save money anywhere that it can, including dropping support for a device earlier than they should.
Developers who arent motivated by profits do not have such conflicts of interest. They are doing it because they enjoy it and for reputation. Even then if they do stop their development, because it is open source anyone else can pick up the project where they left off.