> A company called Ambriosa in particular matches older people with younger people for blood routine blood transfusions.

All sorts of interesting setups could come out of this, with the rich paying the (compatible) poor for their youthful blood. Especially if compatibility is genetic, you'd potentially have multiple generations of a poor family existing specifically to support an aging rich person (and potentially the rich person's offspring).

Depending on how time consuming the blood contributions are, this could turn into a vampire-esque caste system, with the poor being blood cattle.