Instant power down, at any price, is contrary to one of the design goals of Steem, which is, as a noob- (or to use a less loaded term, mass-market-) friendly blockchain, to give users some reasonable protection against hacks.

If your account is hacked, the most you can lose is the liquid funds in your account and possibly one power down installment in progress. If you don't discover the hack within 3 days, you can also lose savings. If you don't discover it for a week+, then you can lose multiple power down installments. Still, you can get your account back within a month, and if you discover the hack quickly, most of your funds are recovered too.

With any sort of instant power down, poof, your account's value is gone in a flash, and while a burn fee would need to be paid, the hacker still gets to keep 80% or 95% or whatever.

To be perfectly clear, I'm not entirely in favor of this "protect people against themselves" model, but many stakeholders are in favor of it, and, as I understand it (though not speaking for them), so are the devs.

So, I would expect that any form of instant power down would have a lot of obstacles to being adopted.