[danShumway]

Google has shown it's willing to force the issue on other parts of Androids -- particularly shipping Google Play with default apps. You can make an argument that's anti-competitive, or against the spirit of Open Source, but regardless, Google is willing to do it.

Custom kernels definitely aren't the only reason why the Android update situation is bad, but they're also definitely a nontrivial part of it. A hardline policy that kernel patches had to be pushed upstream if you wanted to brand as Android with Google Play would probably go a long way towards improving that situation for everyone.

Qualcomm would either say yes or all of their proprietary chips would become nonviable for the smartphone market.

Linux itself can't force that issue because they don't have an attractive brand and suite of basically mandatory proprietary services to take away from smartphone designers who say no. The only thing Linux can do is make life more hellish for people maintaining userland drivers, which companies don't care about because they're not interested in maintaining their stuff to begin with.