Silverlight already has some 3D support and the next flash beta will include a full programmable shader pipeline (using CG I think).
So there is some tough competition and with Flash reportedly having a ~97% of the web install base (bar iPhones/iPads which I am still unsure whether that will be an issue or not only time will tell) and a very large developer base it will be interesting to see what will happen.
So there is some tough competition and with Flash reportedly having a ~97% of the web install base (bar iPhones/iPads which I am still unsure whether that will be an issue or not only time will tell) and a very large developer base it will be interesting to see what will happen.