Let's rationalize it a bit, try to deduce from the information we have so far.
Zoro will be the strongest swordsman, surpassing the Mihawk. We know that Mihawk is stronger than Shanks through his Vivre card, so Zoro will be two power points above Shanks in the end.
Roger was not the strongest man, this was Newgate and we know this from his Vivre Card.
Shanks Vivre Card says he is strong enough to stand beside Newgate.
Now let's think about it, Zoro will be ahead of Shanks since overcoming him is just a prerequisite to be able to fight Mihawk, Shanks is treated as someone capable of fighting Shirohige, so I leave the conclusions with you.