It's not like sony didn't tried...
if my memory serves me right some exploits are unpatchable, I mean they eventually did with hardware revisions but some new exploits were found.
Nowadays sony probably doens't care THAT much, eventually the effect may be the opposite, sony may stop investing the already minimum time and money they do on it and if there are developers still working on ps3 some new things might be found, if you look at the psp it is a very good example; things before thought impossible were actually made, like full cfw implementation before only possible in 1000 and some 2000 models are now available on all systems