Since PH we have been reading about the downfall of the old and the comming of a new Era, BM and Kaido the two monsters of this old era have to be defeated for the Worst generations to really show how they will turn the world upsidedown, and who better to deal with BM than the other two members of the WG with more focus, Law and Kid, a D. and a Conqueror.
-Teach was behind the fall of WB
-Then Luffy takes Kaido
-Law and Kid take BM
Of the emperors BM is the one that is closest to fall, she already suffer a moral defeat in WCI, two of her main executives were defeated by Luffy, her castle destroyed and the idea of living in Totland under a Yonko protection ended, her Empire is already collapsing because of Worst Generations actions, in this case Luffy and Bege, nothing better, or worse for her, than Oda making Law and Kid beating her, this would put them above most of the Pirates, but not high enought as Luffy who will beat Kaido alone and form a trio with Shanks and Teach as the three main Pirates of the present.
Many say they aren't strong enought, but thats the case in all arcs, they start weaker than the enemies but grow strong as they fight, thats how people become stronger in OP verse, by fighting stronger opponents.
I would recomend for the Emperors fans to start to cope with the idea of theirs favorite characters being defeated, because that is the main reason they are in the story, for them to lose to the New generation.
The duo against BM would get them a good amout of increase in bounty, but not enough rival Luffy increase, with Law and Kid getting to something between 1.5b to 2b, but not more than Teach, and Luffy going to 3b for dealing with Kaido. Them Teach probably going to over 3b for whatever he was going after.