There are more than 41 million PS3 consoles worldwide. Only a very small number of which will ever be jailbroken - we're talking half a million to a million at most. The majority of owners simply don't have the technical knowledge, the courage or even the desire to jailbreak their console.
More than 350 million PS3 games have been sold worldwide. Sony gets a licence fee for each copy sold. TBH it was the only way that Sony could make a profit from the first versions of the PS3 which were sold below cost. Since the console is less of an issue financially, the profit is rising exponentially.
Sony will have to be mature about what they do to try and plug security holes. They can't make FW updates network only as not everyone as broadband, how would owners of brand new consoles update? No broadband would mean that every new game released with a FW requirement higher than that already installed could not be run on even recently acquired consoles.
Sony could potentially scan harddrives for illegal copies of software, but it was Sony that produced the first set of instructions telling owners how to upgrade the drives. That means pirates could run one harddrive for use on PSN and another for illegally copied software. It would negate the need for more than one console.
Sony could embed specific code into OFW that allows PSN access. Unfortunately, as proved on the PSP, CFW only needs to patch certain parts of the OFW.
Sony could stop all support for the PS3 and move on to a PS4. Sony then runs the risk of alienating all of the software and games developers who would suddenly be without a revenue platform. The PS4 would be left with Sony as the only software developer and fail to sell any games.
Banning consoles from PSN based on a MAC address will lead to mistakes being made. It will also stifle another important revenue stream; not everyone can afford to buy a brand new console. Sometimes, secondhand is the only way some users can get a console. A proud owner plugs in and finds that they own little more than a paperweight that can only play very old games. As their console has never had any hardware modifications how would they know why it had been banned?
So Sony are stuck between a rock and a hard place. They could use a sledgehammer to crack a nut and try everything to stop the small number of PS3 owners that are intent on committing piracy. Alternatively they could use the Microsoft Windows method; accept that piracy exists andtry to address the problem, but ultimately rely on the fact that the majority of users will be legitimate.
The security on the PS3 was broken because Sony adopted a complacent attitude. What's done is done and Sony cannot recover from this particular fumble.
Nothing is 100% secure if it relies upon human interaction.