Yeah I personally think Blackbeard will be the final villain. So maybe the Laugh Tale fight is against the Kid pirates?
I think it would make more sense if Kid already has 2 poneglyphs under his name, gains a 3rd one in this arc and the minks offer the last one to him. Maybe then out of respect for Luffy or just for the challenge tells Luffy that Shanks has the last poneglyph