It all sounds very bad, but the truth is, we're going to get there anyway - in fact, we're half-way there, thanks to the influence of media conglomerates pushing DRM, adtech living off surveillance economy, all the other major tech vendors seeking control of end-user devices, and security industry that provides them all with means to achieve their goals.
Somehow, no one is worried about the economy. Perhaps because it's the economy that's pushing this dystopian hellhole on us.
We're nowhere near there. Even on the most locked down devices we have, getting computation past the gatekeepers doesn't require reviews remotely detailed enough to catch attempts at sneaking these kinds of computation past, or even making them expensive, and at no point in history have even individuals been able to rent as much general purpose computational capacity for as little money.
Even almost all the most locked down devices available on the market today can still either be coaxed to do general purpose calculation one way or another or mined for GPU's or CPU's.
No one is worried about the economy because none of the restrictions being pushed are even close to the level that'd be needed to stop even individuals from continuing general purpose computation, much less a nation state actor.
This is without considering the really expensive ways: Almost every application you use can either directly or in combinations become a general purpose computational device. You'd need to ensure e.g. that there'd be no way to do sufficiently fast batch processing of anything that can be coaxed into suitable calculations. Any automation of spreadsheets or databases, for example. Even just general purpose querying of data. A lot of image processing. Bulk mail filtering where there's any way of conditionally triggering and controlling responses (you'd need multiple addresses, but even a filtering system like e.g. Sieve that in isolation is not Turing complete becomes trivially Turing complete once you allow multiple filters to pass messages between multiple accounts).
Even regexp driven search and replace, which is not in itself Turing complete becomes Turing complete with the simple addition of a mechanism for repeatedly executing the same search and replace on its own output. Say a text editor with a "repeat last command" macro key.
And your reviewers would only need to slip up once and let something like that slip past once with some way of making it fast enough to be cheap enough (say, couple the innocuous search-and-replace and the "repeat last command" with a an option to run macros in a batch mode) before an adversary has a signed exploitable program to use to run computations.
There's also the bomb every datacenter doing AI thing that LeCun has proposed, which is a lot more practical than this. Or perhaps a self replicating work that destroys AIs.
This was why I pointed out that if I was a nation state worried about this, I'd host my AI training at the cloud providers of the country making those threats... Let them bomb themselves. And once they've then destroyed their own tech industry, you can still buy a bunch of computational resources elsewhere and just not put them in easily identifiable data centres.
We put our servers in datacenters for a real reason, not just for fun though. Good luck training an AI when your intra node communication is over the internet (this is obviously a technical problem, but the truth is we haven't solved it).
Somehow, no one is worried about the economy. Perhaps because it's the economy that's pushing this dystopian hellhole on us.