This question shouldn't be being downvoted as much as it is- it is a legitimate question although would probably go better in its own set in the open thread rather than a discussion section.

Yes, this has been discussed a fair bit- the main argument in most transhumanist circles when this comes up is that everyone will get the benefits and that birth rates will go down accordingly (possibly by enforcement). In that regard, there's a fair bit of data that humans birth rates go down naturally as lifespan goes up. There are other responses but this is the most common. It is important to realize that it is unlikely that this issue will need to be seriously addressed for a long way off.