If you have not heard... then you probably don't have electricity and so it doesn't matter.
Sadly, this may indicate a problem with his health and I wish him the best. I think Apple will be fine under Tim Cook because if you think about it, Cook has been at the reigns several times since Jobs has been having health problems dating back to 2004.
And I'm sure the rest of the management team is as key to Apple's success as much as Jobs. 2014 is where we'll see how Apple can evolve without its top guy. Although... if he can stay healthy, being Chairman of the Board is probably just as effective.