Don't Update
A note to people interested in the exploit and retaining OtherOS support, DO NOT UPDATE. When 3.21 comes out, I will look into a safe way of updating to retain OtherOS support, perhaps something like Hellcat's Recovery Flasher. I never intended to touch CFW, but if that's how you want to play...
Wait, you are removing a feature?
First off, I want to apologize to all the people who use Linux on their PS3. Before releasing, I weighed the pros and cons, and considered the possibility of an impact on OtherOS support. My logic was this. OtherOS support had already been removed from the Slim(not for technical reasons; I believe it only existed in the first place to promote the Cell for IBM) The builders had apparently no intention of including it in future products. So for the purposes of openness why not release? Not like anything else has(or probably will be) done on the PS3.
Now you go and remove a feature that people expected to be included with the expensive device they purchased, citing "security concerns". What security concerns? It's not like the exploit can be run even close to without the users knowledge. You have to open the fucking thing up. How could this harm users? Your blog post doesn't list positive reasons for upgrading like I think most users expect. Instead it lists things you will lose if you don't upgrade. Seriously?
The PlayStation 3 is the only product I know that loses features throughout it's life cycle. Software PS2 emulation, SACD playback, and OtherOS support are all just software switches you can flip. It's unbelievable you would go and flip one, not just on new boxes you are shipping, but on tens of millions already in the field.
Again I'm sorry users. Sony, I expected more from you.