This is all rather confusing
For a start, there's nothing (in principle) you can do with WebAssembly that you can't do with Javascript - expect being able to port existing self-contained code from other platforms. There isn't intrinsically anything there to solve incompatibilities between different environments - it's just that your compatibility layer might be easier to cobble together and run a bit faster in WebAssembly.
Secondly, if you're planning to use WebGL to do your own rendering, then there's a slight problem that a lot of devices on which iPlayer runs don't have a GPU as such ("smart" TVs, for example) and, indeed, have the minimum CPU they can get away with.
Thirdly, if you plan to get round that by rendering your UI in the cloud, who exactly is going to pay for that when the BBC doesn't have the money to fund its existing TV channels adequately. And the same of course applies to personally-tailored content: someone has to write it and engineer it and it's going to be more expensive, cripplingly so if you can't sell it on to multiple other markets because it's dependent on iPlayer.
Fourthly if you're doing your own UI rendering to avoid trivia like "CSS variations", what happens about accessibility?
There's no fifthly because I don't want to sound like Kier Starmer.
I get the general impression that the BBC is trying to play in a space where it has neither the scale nor resources to compete and has no realistic view of its likely future.
Biting the hand that feeds IT
