Luffy and Teach have literally not seen each other ever since Impel Down, it's basically both fucking over the world while steadily raising to top. The build up is the longest by far.
Oda will make their encounter as emotional as it can get. Hopefully Teach never uses Haki so it can aesthetically fit the theme of peak dreams/fruits vs peak willpower/Haki.
The closer this gets, the closer One Piece is gone.