"QA cycles can be shortened. That is "merely" an engineering problem that can be solved: automation, parallelization, smarter tests, and better test plans. Not to mention better code review. There's a whole stack of books on continuous delivery & deployment out there in your library."
If you can make this model work, you have a brilliant edge over the competition. Feel free to try.
"I'd never have expected that, of all people, the _Linux_ folks would be the ones to claim that Linux/OSS can't work in an mission-critical environment but needs to be curtailed to a legacy "enterprise" model! I'm truly amazed."
Linux can certainly work in a mission critical environment. The debate is not about that at all but whether the current enterprise model is legacy or necessary. I would say that it is possible to tweak the model and vendors occasionally do that but it is not going to go away unless some vendor decides to provide a sustainable alternative.