title_body: Do old UTXO's ever get pruned from the blockchain?
upvoted_answer: No, it never gets pruned. One of the appealing features of blockchain is that the history stays there forever.
  The size of the blockchain grows roughly linearly (ignoring the effect of adoption), whereas storage capacities follow Moore's Law and grow exponentially. So the expectation is that, yes, the blockchain will grow bigger and bigger, but that that is no problem, because hard drives get bigger (and cheaper) faster.