Ehhh hes the Worlds Strongest Swordsman bro.
Until Shanks randomly pulls haki arms from his arm stump or decides to not use his sword fighting Luffy or something, Mihawk is considered the stronger fighter.
Ultimately its up to Oda how much he wants to hold it as the truth or lie to the fanbase in the future. Im saying this as someone who still thinks Shanks has the potential to be the endgame, that its only happening if Oda decides that Roger/Shanks have more up their sleeve. If not, then its not happening.