I think it could go this way:
Luffy deals with the marriage thingy somehow, no idea how yet.
They got a call on the denden mushi, it is Law or Zoro, panel shows them standing above the defeated Shogun "Kaidou is not here, he is going after Shiraoshi, he knows about her power, she is at the reverie"
Boom.
while the whole kaiodu goesa to the reverie thing has been a theory of mine since,well since x-drake captured him,oda doesn't seem like the guy to skip potential arcs toriko-style
Theory: Big Mom is Luffy's mom. Sanji becomes Luffy's brother in law. Big Mom allows Sanji to continue with Luffy because he's family.
all the reaction big mom had to the family name "monkey d." was to connect him to garp..so it's not possible that she is his mom..it's not a case like with ace that had his mother's family name and so we didn't know who his father was and him being roger was a surprise
luffy might be able to take down big mom depending on the kind of people that show up to the wedding. if what pekoms said is true then many that show up to her parties only go because they are afraid of angering her if they don't show up. that means that many might betray her if they could become allied with somebody with the strength to take her down. on the other hand luffy might be able to ally himself with a ton of powerful pirates at the wedding and bring them back with him if he goes against kaido. the wedding arc might be a second power up arc for his alliance.
i don't think so...defeating a tonkou has been presented as a big deal,really big,so no way luffy it's gonna dispose of one with a team of 6 and a couple of other characters that might be added later while an entire army has to be created and a plan with steps has to be performed to get rid of kaidou...don't forget that yonkou are suposed to be kind of at the same power level,since the first definition we had of them was "the pirates that could be considered on par with whitebeard"
also,we are going into the lion's den at this point...weddings are supposed to be this big thing with tons of guests..so not only all of big mom's crew will be there (it's their base anyway),but also probably all the allied pirates,the high ranked goons,plus all the vinsmoke family ,with god knows how many competent fighters
while i'm sure that some fights will happen in the next arc,luffy it's not gonna burst from the front door and fight everyone,it's suicide
anyway,i'm really pumped uup for this whole cake arc..the setup is good and there are many possibilities..just hope oda is gonna live up to that,since lately he has been godly in the build up,but the resolution has not always been on par to that