It's a newbie asking the question so no I don't think it is a joke.

the short answer is the addresses will not run out.

bitcoin is designed to have far far far more addresses than will every be required.  therein lies its security.

assuming the hypothetical, that there was a collision and you created an address that was already in use then you have direct access to any funds at that address (unspent outputs sent to that public key). However the probability of that happening is so low that it is impossible (see other threads for comparisons to atoms in the universe etc).  We are not talking about winning the lottery odds here, these odds are far far lower, more like winning the lottery in a trillion years type of probability.

Even if only 1% of bitcoin addresses were used up then bitcoin would be considered well and truly broken.