So it seems that Oda's hint about 'that' man fighting 'that' man, was hinting to more than 1 fight
Seems it was a generic statement yes. An actual free for all:
- Luffy vs Kizaru (likely)
- Shanks vs Kid
- BB vs Law
- Aokiji/BB vs Garp (?)
Assuming we actually go to Fullalead and Elbaf after Egghead, Im not entirely sure who would be the direct antagonists in both, but I have a big feeling that outside of Luffy defeating an Admiral if it happens, BB and Shanks will win their fights and move on from Fullalead and Elbaf, heading closer to Lodestar. Regardess, Luffy probably gets to Fullalead/Elbaf during or the aftermath of whatever was going on there before moving onto Lodestar.
Then, personally, its a 3 way race to Laugh Tale between Luffy, BB and Shanks.