I can’t see a way that anyone would be able to give uncapped access to these models for a fixed price (unless you mean it’s scoped to your own use and not for company use? Even then, that’s still a risk to the provider.)
As a consumer it seems to me the low hanging fruit for these super-premium offerings is some substantial amount of API credits included every month. Back when API credits were a relatively new thing I used LLMs infrequently enough I just paid $5-10/mo for API credits and used a desktop UI to talk to ChatGPT.
Now they want $200, $250/mo which is borderline offensive, and you have to pay for any API use on top of that?
Putting API use into the monthly plans doesn't make a lot of business sense. The only people who would sign up specifically to use API requests on a monthly plan would be looking to have a lower overall bill, then they'd pay-per-request after that. It would be a net loss.
I use Msty a lot for personal use. I like its ability to fork conversations. Seems like a simple feature but even ChatGPT's UI, which everyone has tried to copy, is fairly limited by comparison.