Even if that "dream" comes true, which is really really diffficult, basically impossible, still there is that snowball in hell chance, things don't change. There is a reason if I always put "Dressrosa" before Doffy. And anyway it is like comparing Labasta Croco and Marineford Croco, powerwise they are entirely 2 different things.
That would be the biggest ass pull in op. Mingo is chained to a wall and can't even move. If anything he should get weaker than he was not stronger. By the point if he even escaped both Luffy and law should be far beyond what he was. I still think if he does escape him helping BB would be interesting not him being on par with kaido.
Yea croc was also training while in prison and was getting back to his prime self not the shell of himself wb left him. Mingo is literally chained to a wall and can't do anything. If he comes back stronger or worse yet near luffy that's the biggest ass pull of op. He can't train his body, haki, and already had awakening. So there's no room for him to grow and he should be getting weaker not stronger.
Well there is a huge reason from that. First of all, Croco was not weak. His basic attacks could already cut steel with ease, feat that Zoro had to use Haki to be able to do so.
And then, the power of his DF does not depend on his physical power but with his skill which he said he fully mastered, reason he could cut Akainu and do some othe great feats in Marine Ford
Then, in Alabasta, we saw the weakest version of Croco, just look at how weak Moriah was considered when he stopped trusting in his abilities and relied on making a inmortal army? He was aimed to be deleted. The same happened to Croco, but unlike Moriah who didnt change, Crocodile's defeat and meeting Luffy changed his will to keep dreaming and getting stronger, AKA version Marine Ford Croco.