I think I understand what you are talking about, if you are exceptional then you will always have ideas and oppourtunities. Take Mark Russinovich for instance
. But if you are a typical senior system software guy like me, you are limited to co orporations/companies. Another idea would be to act as an idependent consultant if you have good contacts.
As for me, I love what I am doing and do not want to start anything my own at this point. My hope is that as long as there is system software, there will be crash dumps for me to poke into