I'd love it but with Oda wanting to wrap up the story I'm not sure he can allow himself to make that move. it will make the story longer. Unless Shanks is the final boss who allies with the WG and Im.
I personally believe Shanks is the final antagonist (beyond BB, WG and Marines).
It's not about him getting a separate, localized arc after Wano. Its about all of this culminating into a big final war. For sure we still have Elbaf and Laugh Tale left at least, but I don't believe those will have anything to do with Shanks being an arc villain there.
We have to get out of the mentality that there will be full arc villains after this point. Maybe Elbaf or Vegapunk, maybe Laugh Tale, but it's not guaranteed anyway