As a vehicle for piracy then, all bases are covered, but is this really a "jailbreak" in the form recently sanctioned by the US courts? The mere existence of the backup manager - supposedly coded with tools stolen from Sony - would suggest otherwise, and if the USB dongle is indeed cloned from the platform holder's own recovery tools, any pretence of legality is surely a joke.
The presence of the PKG installation option does indeed mean that the likes of emulators and media players could be ported and installed on to the PS3. However, for now it's almost certainly the case that Sony's own dev tools would be needed to make any kind of useful application, adding to the legality quagmire.
All told, it's a nightmare scenario for Sony - but you can be fairly sure that its response will be swift. We can fully expect a mandatory firmware update to emerge from its engineering labs within days of the firm dissecting the hack, doubtless rendering it useless. Damage limitation will be the key, and similar to the OtherOS removal that Geohot's exploit brought about, Sony will be looking to minimise the physical amount of consoles available capable of running the hack by effectively upgrading them out of contention.
Assuming the memory patch theory is true, the swiftness of the response shouldn't be an issue for Sony's engineers. Changing the make-up of the modules affected would be child's play for the platform holder and it would almost certainly necessitate a much higher effort on the part of the hackers to reverse-engineer the new code and re-patch it. Additionally, over the longer term, there is nothing to stop Sony from introducing brand new forms of encryption and execution on the way that future games boot.
However, the properties of the USB dongle itself may well be more difficult to defend against. Assuming that the device itself is derived from Sony's own servicing tools, it may well require a complete, brand new revision of motherboard to successfully defeat. The whole purpose of the dongle is to restore corrupt firmware - the chances are that it has to operate on a hardware level that cannot be touched by the updater. We've seen it before on Sony kit - the so-called "Pandora" battery for PSP that flips it into service mode operates on the same principle, and was only defeated by the platform holder when it revised the handheld's motherboard. Nothing could be done to protect the existing devices.
Unless Sony is capable of rewriting the most basic low-level code on the PS3's BIOS, there's little it can do to defeat the USB vector of attack - it's all about preventing the injected code from working. Going forward we can expect the usual cat and mouse game between hackers and platform holder to unfold, and it's not beyond the realms of possibility that in the future, Sony will be able to detect users of the device and rightfully ban them from accessing PSN, similar to the measures Microsoft continues to undertake annually against gamers who flash their DVD drives to run copied software.
The complexity of Sony's security systems suggests that it will be able to keep one step ahead, but there is nothing to stop people using the hack to prevent firmware upgrades from taking place. Indeed, the chip itself is said to protect the console from executing system updates. This of course precludes PSN access, and in the fullness of time this approach will stop newer PS3 games from running as they will be reliant on software elements found only in the newer firmware.
Bearing in mind that PSJailbreak is retailing for upwards of $130, there's a very strong possibility that this may well be the most expensive and short-lived hack ever made, and factoring in the simplicity of the hardware, the very high price seems almost reminiscent of a smash-and-grab raid on users intent on piracy no matter what the cost. The makers of PSJailbreak are charging so high a price because the window of opportunity in terms of exclusivity and the longevity of the hack itself is potentially very small.
That said, the exact properties of the USB stick and how how future-proof it is remain unknown. With mass-production of PSJailbreak now in motion, and the first retail devices apparently set to ship before the month is up, Sony's engineers are doubtless gearing up for the battle to come.