He's not ready for a Yonko. Current Luffy is slightly above Vice-Admiral. Also Luffy is taking on Kaido not BM I'd say this is how it goes.
Kaido vs Luffy: Kaido wins no-diff
Kaido vs Ace: Kaido wins Low-diff
Kaido vs Marco: Kaido wins Mid-diff
He's nowhere near a yonko yet. 2 Years isn't enough to turn Mid-Tiers into Top-tier. Luffy says he'll beat all of them. He always says these kind of things and it's very likely that he wont be beating them for a long time.
Kaido vs Luffy: Kaido wins no-diff
Kaido vs Ace: Kaido wins Low-diff
Kaido vs Marco: Kaido wins Mid-diff
He's nowhere near a yonko yet. 2 Years isn't enough to turn Mid-Tiers into Top-tier. Luffy says he'll beat all of them. He always says these kind of things and it's very likely that he wont be beating them for a long time.
