We could get a few more looks into that era.
I agree with the idea that we'll probably get a little more of a glimpse of Roger finding Laugh Tale and the reason for his laughter.
And, yeah, Shanks fighting someone is another opportunity to see a bit more about the Roger Pirates. Mihawk, or Blackbeard, or Loki, or Shamrock and Garling, or someone else entirely.
Plus, the Man Marked By Flames could potentially have a tie to the Roger Pirates. That could go either way, but I wouldn't be too surprised.
Plus...we really haven't explained ANYTHING about Buggy or where he came from or how he joined Roger's crew. So, I guess whenever we delve into the pasts of most of the Cross Guild leaders, we'll probably flash back, at least briefly, to learn more about Buggy.
So, yeah, we might be in for a few more glimpses of the Roger Pirates and their generation. I don't expect any of these to be as long as the God Valley Flashback. But, who knows? Maybe Buggy has a surprisingly complicated backstory.