So, there's only a minority that makes use of hardware-accelerated HTML5 canvas. 28% can't play at all, and for the rest it is terribly slow (<10fps).
Where are you getting your figures for "a minority" from? Over 50% of the web is Firefox or Chrome which both support WebGL with fallback to hardware-accelerated 2D canvases. Of IE, 10% is now IE9 with hardware-accelerated 2D canvas. Obviously IE8 and earlier aren't supported, but the browsers which don't have hardware-accelerated HTML5 gaming are now in the minority!