I don't see why it would be less secure, reliable, or performant. It might be that the new ideas, and new abstractions, make it harder to do things in insecure or unreliable ways.
Reliability problems: You're going to be porting a lot of programs to this hypothetical OS. The porting process is going to be difficult and error-prone by definition, because the proposal was to make significant changes to the kernel API. This leads to...
Security problems: When you change the fundamental assumptions of a program, you open them up to security flaws. I am primarily referring to ported programs when I say "the new OS will have security problems."
Performance problems: The performance will be worse than existing OS's, because drivers that work for Linux probably won't work for this new OS. This means you're going to have to get by with slower video drivers, at least initially.
These three types of problems aren't impossible to overcome. I doubt 2,000 years from now that people will be using Linux, BSD, or Windows. But you will have to overcome them.
