When Blackberry was on top of the world it was economically plausible for them to have their own OS kernel and userland. But the critical mass to support that is very high, and Blackberry may not have that any more.<p>Blackberry OS also does not have a managed language runtime. It's not an app runtime that's going to attract developers for innovative capabilities or ease of development.<p>Blackberry does have a messaging and email infrastructure, but the compelling reasons to use it are mostly obsolete and uncompelling to new customers.<p>Lastly, Blackberry used to be the cheaper "junior" smartphone. But Nokia is somehow selling a Lumia for an all-up price of $149, unsubsidized, in t-Mobile shops, which makes it the cheapest way to get on a cheap T-Mo smartphone plan.<p>I think they are done. I don't see a way back.