Flash isn't open or a cross-platform standard. They have yet to implement anything like this in the mobile space yet because of all the hardware variations.
Putting it at the browser level in HTML5 solves all those problems for the most part.
I don't think those are the problems that led to the "failure" of podcasts and companies like odeo. Sure they are nice problems to solve, but they don't fix the real issue.
Odeo tried to solve the wrong problem. iTunes and tools like GarageBand solved the content and distribution problem. Odeo was never going to compete with that. What was needed was a scalable solution for monetizing podcasts that worked across platforms.