However I will admit that Oda didn't need to drag this flashback out to this chapter, even last chapter didn't need to be a flashback chapter.
The only reason why I can understand last chapter is because of the stuff with Bonney, but when it comes to this chapter it feels like Oda just wanted to drag it out one last time for the end of the year.
So that way the very first chapter of next year will be back to the present.