I honestly am surprised Oda didn't go this route with Big Mom and her gluttony and being such an easy way to defeat her potentially. Maybe have her being force fed a 2nd DF. I remember people suggesting she should have been fed a DF secretly in her cake at WCI but Sanji NEVER would have allowed that, he was against poisoning the cake too ofc!
We definitely need to see this happen for sure. We need to see if the myth of dying/exploding after eating 2 DFs is true or not and thus it would retroactively add a lot to Blackbeard getting Whitebeard's DF too somehow. Unless Blackbeard used some kind of loophole to gain the DF without facing the consequences of eating 2 DFs, whether its due to his darkness fruit somehow, his "strange body" that might be multiple souls/personalities or whatever or and even some secret knowledge that he and barely anyone else will know at most ofc.
Imagine we see someone eating 2 DFs and they do explode/die and thus proving the myth definitively, which will throw all kinds of chaos and mystery on top of what we already have of Blackbeard getting the Gura Gura!