I think this a really neat idea and for some could be an alternative or addon to the average VPN provider. I did not read all the comments in the other thread but found anti-malware mentioned as a use-case. I have been thinking a while about some more advanced anti-fingerprinting/tracking techniques. In many cases you can be fingerprinted even if you change your IP. Some kind of cloud browser or desktop which randomizes your browser, underlying OS, IP + all the other stuff which can be used for printing, would be awesome. In principle tinkering together something like that should not be that hard. Maybe automating and maintaining the whole setup.
There is https://www.bromium.com/our-tech/bromium-secure-platform/ which isolates each tab in a VM, Would it be possible to isolate each tab in a different cloud server? i.e. in tab 1 I'm aptrgangr on ycombinator with edge on windows, in tab 2 I'm lurking as uptrgungr on irc with firefox on MacOs, in tab 3 I'm writing my business mails with chromium on linux. I'm not sure about the isolation of those 3 identities though, when everything is running in the same browser.
I don't know if you could setup up kind of a light version of this model: for example open this link in a new tab but with a different IP, user agent and other factors which could easily be used for fingerprinting.