We have been using and building WordPress sites since 2006. I have no experience with WP Engine but I bear them no ill will. I think the "court of public opinion" is very difficult to assess and dominant players can take a very very long time to die.
Matt may need to step down if your assessment is correct but that's distinct from what happens to Word Press as a platform.
My sense is that the Word Press negotiating position is stronger and WP Engine will either have to fork or make a much larger contribution. But I may be wrong. If that does not happen then I believe that the private equity players will do a lot more damage to open source communities because a "harvesting paradigm" will continue.