I’ll try to keep it short and simple. So we know that the Big Mom’s crew is in shambles right now and was so even before the Germa 66 attacked.
But this doesn’t mean that they are weak without Big Mom, just because Luffy was able to defeat their top fighter. I believe the Straw Hats’ strength is what makes up for the weakness of the Big Mom Pirates. Straw Hats derive their strength from caring for others, while a lack of care and love from Big Mom herself and even among the siblings was what made their otherwise strong structure full of holes which the Straw Hats capitalized on to bring the Yonko crew to its knees. In a straight up fight Straw Hats couldn’t stand a chance, but due to this lack of love from Big Mom and disregard for family made it easy for the Straw Hats to find allies within the structure and use it against them to gain the upper hand. Jinbe, Pekoms, Pudding, Praline, Chiffon and most importantly, Bege were the key to Straw Hats’ victory.
Now, a similar kind of relationship can be seen in Beast Pirates. Kaido doesn’t care for his subordinates and only sees them as a tool to meet his end and so does Jack.
Doflamingo knew he’d be killed if he couldn’t supply Kaido with any more smiles and X Drake’s crew was afraid just to even tell Kaido the news of Doflamingo’s defeat directly. Such kind of system works on fear and not on loyalty, which means there might be a lot of potential allies within the Beast Pirates for the Mugiwara and a similar weakness in the structure for them to exploit. Kaido maybe immortal but definitely isn’t undefeatable.
And this is where Shanks and Blackbeard’s crews come in.
Even though we know that Blackbeard is one of the most evilest guy in the series, and did kill his comrade, he did that only to obtain the devil fruit. Blackbeard doesn’t run his crew on fear and treats them nicely and respectfully. His crew doesn’t seem to fear him and loyalty aroused in them is out of respect and admiration for their captain. As for shanks, we know how his crew is. It doesn’t need explaining. As far as the strength of their captains are concerned both Shanks and Blackbeard are immensely powerful on their own right, strong enough to earn the title of Yonko on just their individual strength. What I’m getting at, is that both of their strength is comparable to Kaido and Big Mom. Furthermore the strong bond with their crew only makes them that much stronger unlike Big Mom and Kaido’s crew. There won’t be any weaknesses to be exploited. So when the crew goes against either of those two, only then the real strength of a Yonko will be showcased.
So what I’m saying is that the Big Mom crew is essentially defeated, and if the Kaido crew will be defeated by the Alliance, that doesn’t mean that the Straw Hats and Law alliance(probably Kid will join too) would’ve reached the pinnacle. They would still have a long way to go. Shanks and Blackbeard will still be at a platform unreachable by the Straw Hats and co.
*Theory by TheInvisibleGuyZ