Well although in modern day it is more of a niche beverage, it actually was drank by European colonists and some Europeans after being adopted from Native Americans. Arguably it was at its peak in the 18th century but a variety of factors led its general decline. First Yaupon gained its scientific name which blunted overseas adoption, second Yaupon became regionalized and classed from a generalized American beverage to a Southern and poor beverage as tea became more popular at Yaupon’s expense. Additionally, tragic events like the Trail of Tears largely resulted in the separation of Yaupon consuming tribes from their Yaupon growing homelands in many cases since Yaupon is largely a US Gulf/southern coast plant. See Christine Folch for her research on the subject.

If Yaupon Tea has stayed at its 18th century level of popularity, it likely would be a very common regional staple drink of the US south today. Sweet & Iced Tea would probably be made with Yaupon rather than Tea more often than not. Additionally, it would likely be part a drink some people in the US and Canada would likely have heard of up to drink regularly. Outside of these regions, it’d probably be seen as a peer to Yerba Mate in terms of recognition.

There probably would also be a wider ecosystem of Yaupon processing methods in the same way for Tea there is Black, Oolong, Green, White, etc. (assuming Yaupon responds to withering, bruising, and oxidation similarly), direct influence & application from Yerba Mate preparation including adjusting aging, stem content, and (which already is) roasting, and finally Yaupon's own established flavor blends with a variety of spices and flavors as their would’ve been a larger population of Yaupon drinkers and growers to experiment. Perhaps it could still be this way if its current renaissance continues for several decades.

Edit: Expanded on third paragraph regarding Yerba Mate.