How this affect PandaPlugin?
The same way O3D, Unity, and any other in-browser 3-D system affects Panda: not much.
The biggest thing HTML5 has going for it is that it promises to be widely supported and come with your browser. But it’s going to be its own 3-D system, just like all of the other 3-D systems are different. It will have its own strengths and weaknesses.
It will probably have more weaknesses than strengths, especially at first, and maybe for a long time. It would probably be ideally suited for simple, one-off games, rather than anything that requires the finesse of a mature engine like Panda.
So, if your goal is to write some simple 3-D for the web, it’s easily a more appealing prospect than Panda. But if your goal is to write a complex 3-D experience, you should choose the engine with the same care that you choose it today, even with HTML5 in the mix.