If these parties all decided to use whatever codec came out of this, and Apple choose to stay out, it'll be Apple's loss when Netflix, YouTube and the rest start showing messages about "your Apple computer/phone is not able to use this site, please upgrade"...
To their peril. Despite Android outselling iOS 4:1 or more, Android traffic is basically even with iOS, and unfortunately, iOS is also the platform of choice for those with money.
If Netflix doesn't work with iOS, users are more apt to blame Netflix than iOS. Ditto YouTube and others, especially since they work now. Breaking that will cause people to say "Netflix worked yesterday, today it doesn't. Netflix must have done something". And indeed they did.
Anyhow, h.264 is unlikely to die anytime soon - the real reason for this alliance is the mess that's become of HEVC licensing with two different and non-comprehensive patent pools. Whereas with h.264, patent licensors paid per unit until they hit a cap - it's unlimited after that (Apple, Google, Microsoft, Cisco, Netflix, Amazon and others just pay the cap), and streaming is free as long as customers can view the stream without paying (so ads are OK).
The problem is, a lot of the HEVC patent holders were presented with similar terms for HEVC by MPEG-LA, and they wanted out. Specifically, they hated the cap, they hated free streaming, and they wanted to move on.
Doesn't take a genius to figure out that those properties enabled the mass uptake of h.264.