It may happen but for now the 360 isn't hacked... Only the drive is patched to an extend that lets you play backup games.
The original xbox was completely hacked. Custom bios which resulted in playing unsigned code because the box didn't care about the mediaflag or signed executables and such.
MS really raised the pole on the 360. Every communication between the parts on the motherboard is signed and encrypted. Every piece of hardware has it's own key which all are stored in an encrypted keyvault to check against. The bios is stored in the same way as the keyvault.
To really hack the 360 you'd need to break the encryption on the bios and this will only happen if someone of the genuises finds a hole where the 360 exposes the key or if it is guessed (it's more likely to get hit by a thunderbolt 10 times in a row).