Generally hardware warranty will remain if it's purely a hardware issue - you can always flash back anyway.
Android is free software in the sense that you can make and distribute modified versions. If app vendors choose to discriminate against those versions that doesn't make it unfree any more than software supporting windows and not Linux makes Linux unfree
I don't think that's enough to make it free software, and "free software in the sense..." is nonsensical. Free software would guarantee the continuance of that freedom. Since that guarantee doesn't exist, Google could place limitations on the Play Store at any time. The fact that they haven't makes the example less clear, but it doesn't make Android free software. Even Google doesn't claim that it is.
Play store isn't open source at all.
Amazon was able to take Android and put it on their extremely popular devices with 0 support from Google, no play store. That's what I call freedom
Isn’t the entire point of Google’s certification process to encourage app vendors to make that choice?
Citation, please?
Some years ago I had Samsung S2 where unlocking the bootloader was an offline activity. I don't remember how but doing that was quick and easy. Now I own a MotoG4 where unlocking means going to some website, entering my email address and then receiving unlock code in my email. If Motorola knows my email address, or can link the (supposedly unique) unlock code to my phone, what's stopping them from voiding my warranty?
I have a hunch that newer versions of some mainstream phones do not allow unlocking the bootloader, and this is going to become more and more common.
