I'd say the only real "threat" is that someone else shows up doing it better. Aside from that, not much could rock their boat. Third parties come and go, but they came around originally because of WordPress's success. Change in license couldn't happen, no way. Anything else is just too unlikely to be concerned with. Matt is really young and (if his pictures are any proof) very healthy; he's not going anywhere.

@Angsuman Chakraborty - Also, they offer a premium service on WordPress.com, so there is some revenue coming through that project at least. Also, how should the WordPress team leaders be more cooperative to commercial WP developers?