Shanks was always at best equal to Mihawk. He is honestly probably a bit weaker and the newest spoilers make it even more obvious to anyone with a functioning brain.
This isn't an insult the gap is very small like 99 vs 100. Thats why Mihawk does not want to fight Shanks after he loss one arm. He loss all chance of ever beating Mihawk as a cripple.
Sure oda said Shanks didnt become weaker but his potential obviously gets lower with one arm....