I'm no expert on hacked PS3s, have never considered hacking one either but...Okay i get it but 3 more questions
1) if my psn id is banned can a new one be made, and if my ps is banned then will it get dead?
2) linking with these problems cant i even switch on the wifi and browse internet, update games and stuff.
3) finally if i want to play online and stop these jail break methods then how?
1) Your PS3 will get blacklisted, like Beowulf said, and that means you won't be able to play online ever again on that PS3 system. I'm sure that means you can't make another account. I believe they block you from downloading the latest firmware updates and that prevents from you from ever going online on the PSN.
2) I think you'll be able to use the Wi-fi and the PS3's browser but I don't think you'll be able to update games.
3) Once your PS3 is blacklisted, there's probably no way to reverse it. You'd just have to get another PS3. If you HAVEN'T been banned, have a hacked PS3 and wanna go back to the OFW, you're better off asking someone else, I have no idea about it.
Hope I helped, even though my answers were mostly guesses.