All my Theories XD
I think Luffy will battle and defeat Loki at Elbaph. I think Loki MIGHT have a Ponegliph copy, so then Luffy will steal that. Then, theirs the the Laugh Tale Arc! I think all of the major people in the world/The Marines, Elders, and Emperors will follow Luffy to Laugh Tale. This will allow Luffy to fight Blackbeard and Akainu, which will need to happen, and Zoro to fight Mihawk. After that, I think Imu will make an appearance, and everyone will team against them. Just my weird theory. (One last thing, Luffy will die. i bet the series will end with his execution)
EDIT: Revolutionaries will also be their XD