[darren_]

The ars technica article about this has some additional info from the hacker about sony not really being able to do this:

"CTurt stressed to Ars that it would be nearly impossible for Sony to plug the hole that enables mast1c0re. That's because a version of the exploitable PS2 emulator in question is packaged with each available PS2-on-PS4 game rather than stored separately as a core part of the console operating system. [..] For physical PS2-on-PS4 discs, that means the exploit should continue to work as long as you refuse any online updates before playing. And for digital releases, even if the exploit is later patched out, there are methods to downgrade to a stored, exploitable version using proxy HTTP traffic from a local server."

so there isn't just a single PS2 emulator in the PS4/PS5's OS, it's a per-game emulator.

[Sunspark]

If Sony wanted to end PS2 support on the PS5, my theory is that an easy way for them to work around what is described in the quotes would be to simply issue a new system update which then refuses to run the name of the executable or loading a support library it needs to operate.

I believe it is doable, but the long-term impact to consumer loyalty is another question. Xbox is a peer system and people may move to it and potentially not return.