Yeah most of that is browsers and html5 fault. C2 is always awesome, but HTML5 is inconstant. It sucks in some areas, lack in others , is good enough in others , is excelent in a few etc. So C2 is totally dependant on HTML5 success. That represents both a big risk and a huge opportunity for C2 , only time will tell.
About Flash, Flash Player is almost dead. But AIR is moving on and it appears to be a pretty nice framework for multiplatform dev. I don't know what to think about AIR really. It owns HTML5 big time in a sense and sucks at the same time since the hopes are on HTML5 not on AIR. It's a complicated and prone to flame wars discussion at the least.