No, they're not. They're selling a service that allows you to rent content and have it stream to you instantly. The content library is what attracts people, of course, but their core business is selling the service.
"Unless we went back to the big studio era when talent was locked up with multi year contracts"
Erm, they already produce Netflix Originals, which are exclusively locked up on there (and their competitors all do the same thing). How does that differ from your suggestion?
"nothing can stop a Hulu from poaching a great show runner from NFLX"
...and nothing can stop Netflix from getting the licence to a show that used to be on Hulu. Also nothing to stop them both licencing the same show at the same time.
"Its long term success is suspect to me, debt or not."
Just Netflix, or do you also think that Hulu, Mubi, Filmstruck, etc. are all doomed as well? (I left Amazon out because obviously Prime streaming obviously isn't their core market) If just Netflix, what differs in your view that makes them more vulnerable to their competition?