Here's the most reasonable disaster scenario I can foresee: Zuckerberg is not personally invested in the technology, but believes a general audience can make it very profitable. Technical execution of version 1 is perfectly successful. Core gamers generally buy the product, but the larger market is uninterested because of usage limitations (headset size and portability and/or lack of compelling enough uses outside of gaming). However, the number of sales is not large enough to justify continued investment. Facebook needs to find a large buyer to divest themselves of the technology profitably.
If they do not, the patent cache they hold chills any potential competition for fear of developing a market being ripped out from under them.