First off, you aren't going to have to worry about it because Becky isn't going to AEW she is taking so well earned time off from a physically demanding sport. And if she ever wants to wrestle again she will come back to WWE with Seth. Seth is a WWE lifer like Taker, Rock, Austin, HHH, Orton, and Cena. He's never going back to the indies. Ever.
Secondly if she does for whatever reason shock the world and go to AEW then yeah she'll pop a rating. But just like Sasha it won't be as big as you are thinking it will be. There are only 3 active needle movers that actually do draw huge crowds and retain huge numbers and those 4 are John Cena, CM Punk, Roman Reigns and Logan Paul.
People can cry and piss and shit all over themselves trying to pretend this isn't the case. But the coping and seething doesn't change reality.
And soon we will only have Logan Paul because Punk, Cena, and Reigns are in the last 5 to 10 years of their careers. In fact In think Punk and Cena will both hang it up in the next 2 years actually.