I think most of the posts are correct that this has come about because of the over reach of h265 patent holders' demands for money. I have to assume that they can change their licensing terms at any time though. If it looks like they are losing business, it would make sense for them to drop their prices, just like any business venture would.
If the cost of using h265 suddenly drops to the range of using h264, I have to think that at least the speed of progress would slow for the open solution(s). I have to believe it's really hard to create a codec that is performant and doesn't (arguably) infringe on alleged patent rights. At some point, some of the companies in this alliance may decide it's not worth the cost of doing more development if it's just as cheap to pay mpegla (or whomever) to use h265.
I really think that it's good news that this is happening because of a business decision in addition a moral decision. It makes it a much easier sell to the PHB, but as business situations change, business decisions must also change. I really hope that there is enough conviction in this project to overcome issues that have kept previous solutions from following through.