Adobe Flash's clock is ticking, and not in a good way. Apple wants it dead, Microsoft is about to make life for it much less comfortable with Windows 8, and Google supports it, but only to get under Apple's skin. The better that browsers and authoring tools that support HTML5 get, the smaller the remaining market space for Flash becomes.
For Flash to remain viable, Adobe has to position it for applications that can't be done well, or at all, with HTML5. It appears that Adobe has decided to focus on 3D applications with Version 11 of Adobe's Flash Player and Version 3 of Adobe AIR, both of which are scheduled for release in early October. Flash 11 has a new GPU-accelerated 3D API called Stage 3D, which should dramatically improve 2D and 3D rendering rates on devices with compatible hardware. Adobe claims that, compared with the current Flash Player's capability to render thousands of non z-buffered triangles at 30 Hz, Flash 11 will be able to render hundreds of thousands of z-buffered triangles at 60 Hz.
Flash is currently very popular for browser-based casual games, but Adobe wants Flash 11 to be used for far more graphically-intensive games, and has signed up EA Interactive, Ubisoft and Zygna to support the new capabilities in their games. The problem, as Wired's Webmonkey site points out, is that WebGL can provide at least the same level of 3D performance in browsers without plug-ins, and WebGL is an industry standard. However, Internet Explorer currently doesn't support WebGL at all, and other browsers have widely varying WebGL performance.
So, Adobe may be able to carve out a niche with Flash for 3D applications, but it's hard to see it as anything more than temporary. Browser developers will be improving their WebGL performance in parallel with increasing their HTML5 compliance. The real test will be how many developers successfully market games written with Stage 3D.