For people who actually care, I think the concerns are overblown and we'll always have access to a machine that can run open software.
And yes sure, we might not be able to pay consumer prices for them, but they are not going anywhere.
And sure, we might elect a fascist government which will simply ban the technology, or the west will go to war with China making it very difficult to manufacture anything. Unlikely.
Before social media, the average person had little to no interest in the internet - or PCs in general - aside from email and instant messaging apps. The internet has changed, but it's 99.9% because more people are using it, and their interests and needs are best served by 'it just works'.
This change, along with progress in general, has also made life better for technical folks. General purpose computing is dead? Come on. Desktop Linux actually works. Municipal fiber is a thing. Capable enterprise hardware is available online for less than a second hand iPhone, and if you don't have a couple of hundred to spend, a VPS costs less than a hamburger.
What makes you so sure the restrictions will stop somewhere you're comfortable with? What happens when unlocked machines are only available to "enterprise" (not unlike a certain Windows version), and you have to agree to audits when buying them? What chance do free operating systems stand, when 99% of users don't even have access to computers that could run them?
We need not worry as long as somewhere, in some dark basement, a sysadmin is able to assemble an unlocked personal computer from his company's old hardware?
The way to stop this is through legislation and protest, but it's a battle because the state likes locked down computers too.
Right now, today, it has never been easier to just go down to the local mall and buy a general purpose computer, and sure, there are lots of phones, tablets, and consoles on display as well, but there is no less computers as a result.
These regulations can easily outlaw general-purpose computing on the same grounds of being too dangerous for the society. I can remind you how encryption algorithms were considered "munitions" back in 1990s, less than 30 years ago. At that time one would possibly say that it will always be possible to bring a small bottle of water onboard of an airplane. Betting on things always being "naturally" available, without a conscious effort to sustain them, is a fraught enterprise.
The percentage of unlocked computers for consumers has been falling. Consoles, tablets, smartphones (all iPhones and many Androids don't allow rooting), smart TVs... even some laptops. Surface RT laptops had locked secure boot, and Chromebooks made it very difficult to install alternative OSes, as far as I know.
As for the incentives of the "open market", there's profit in locking down devices, and selling you back fragments of that locked functionality. For example, nvidia pushed an EULA that forbade using their consumer GPUs in datacenters, making them buy the far more expensive enterprise versions.
With how markets tend towards oligopolies and monopolies, there's no guarantee the handful of manufacturers left won't conspire to put restrictions on all computers. Especially if 95% of consumers don't care about being able to run gcc.
I don't know why do you think it would? Both software and hardware-side, there's no end of complaints that power users are being left behind. All the money is in making Fisher-Price software for the masses. Ain't nobody have time to cater for ergonomics or efficiency in computing, it's only a distraction from milking the general population.
This, to me, is a clear example of the market underserving a customer segment.
