You won't see Flash 100% removed browser support for a very long time. Far too many backend business and educational solutions rely on, for one, a Flash UI which requires FP funtionality. There are so many communication programs out there used daily by corporate people that have Flash functionality built in.
Search for online Kids Games...ya,
Youtube isn't and never will be the determining factor in Adobe finally throwing out the source code to the public for self support, which is what they'll end up doing at some point, they'll pretty well have to.
Apple? Who cares, yes I use Apple products daily still so not a hater, but Adobe doesn't care what Apple supports as Apple abandoned professional users long ago in favor of, well no one really knows. Apple killing FP support certainly didn't have any real effect at Adobe that's for sure. All it really did was show people how idiotic Apple's 'walled garden' approach is.
On a performance comparative basis, if you think this game plays glitchy and bad built around Flash? This game would have been dead and offline years ago had it been written into an HTML5 environment. Performace-wise it's not even a close contest, Flash wins every time hands down.
So, WGT/TG's concerns on the issue of FP and its game? I doubt there's anyone giving it any real thought at all. No reason to.
Don't foget Adobe themselves stated they'll continue supporting FP for some 10 more years at least, that was in 2015, so still 8 more years roughly of offical support in some fashion. My guess is, long after that someone will pick it up.
*Also, not intended as a contradictive argument starter directed at the OP in anyway.