Was always gonna happen one way or the other.
Oda needs a clear way to have Luffy "surpass" or reach Shanks level, without him actually fighting Shanks. The way Luffy fanboys for Shanks he could never give that man a real fight. Not to mention the fact Oda would never have him fight a top tier swordsman.
As for Shanks bro? Shank-stans better pray that man does not have a black blade cause Shanks identical twin brother who instead of sitting on his ass the past two decades drinking himself silly could have potentially done shit/trained with Garling?
AND has two function arms?
Shit, that guy might be above Shanks by default. If he legit is Shanks twin, he by default has the same genetics and oh so praised God King haki. Since, as we know, Conquerors Haki cant be made stronger, and its just an innate thing you are born with? Shanks bro just as strong as him in that regard.
And since as Shanks-stans like to remind people he is not a REAL swordsman and thus not skilled in blade combat… what are the chances his brother that has been potentially trained by his dad in sword combat all his life is stronger than Shanks?
Pretty decent I would say, but hey, might just be me.