I think your fears are a bit misguided. WebAssembly runs within the same sandbox as JavaScript code. I don't see how this would constitute a _higher_ security risk than browsers as they stand today.
WebAssembly isn't a higher risk than JavaScript — what's a higher risk is increasing the use of JavaScript and/or WebAssembly.
I fear that in the not-too-distant future web pages will simply be blobs of WebAssembly which paint UIs within a browser, and general-purpose computers will have become TV terminals — but TV terminals which allow the modern equivalents of networks & newspapers to steal one's private information.
>I fear that in the not-too-distant future web pages will simply be blobs of WebAssembly which paint UIs within a browser,
Some will, probably, but there's no reason all web pages will go that way. "App" type sites almost certainly, maybe streaming services, but the benefit just isn't worth the cost for most sites.
It didn't happen with Java, it didn't happen with Flash, it didn't happen with Silverlight, it didn't even happen with javascript even though it's possible to publish an entire web UI as an obfuscated "javascript blob" that writes on a canvas. It hasn't happened now that most people surf the web on walled garden Android phones, arguably the antithesis of a "general purpose computer" and closer to the "TV terminal" you described. Why is Webassembly the straw that will break the web's back?
If almost no one actually wants to build the dystopian scenario you're afraid of, and doing so would probably be impossible, why be afraid of it?
I fear that in the not-too-distant future web pages will simply be blobs of WebAssembly which paint UIs within a browser, and general-purpose computers will have become TV terminals — but TV terminals which allow the modern equivalents of networks & newspapers to steal one's private information.