Adobe Flash is declining, I know that. But the content developed in Adobe Shockwave player, what is the future of that content. I want to develop a 3D multiplayer game and I am looking for my alternatives here. So if there are better alternatives than Shockwave, I would love to know.
It isn't declining at a rate that should worry Flash developers, Apple just refused to let it on their devices to protect app-store revenues, and I think people generally acknowledge that now the hype's died down.
Equally, we had some real trouble getting webGL to work on iOS devices, don't think they let you unless you have iAds (though this may have changed) - given that they refuse to let you use any alternatives in-page, this is pretty cheeky!
You can export Flash player files as AIR applications, these can be installed and run on Android/iOS devices (performance not always too great but improving steadily), I would offer this as an alternative for tablet/mobile users, as well as conventional Flash for desktop.
In terms of alternatives, the only serious contenders are WebGL or Unity, you will have to pay for the latter but you get a full 3d development environment, and can code in C#, which is always a bonus.