This is a turning point for the whole series, in more than one way.
Up until now, the mugiwaras(at least luffy, zoro, sanji and robin) have always been stronger than their opponents. They were just put in difficult situations that put them on equal levels with their opponents. Think about it, not one fight has had them really beat in fighting ability up until now(EX. to beat mr.1, zoro had to learn to cut steal, if he could alredy do that, mr.1 would be no chalenge, and if MR.2 didnt have the mane mane montage of nami, he would have lost way sooner.)
this is why the "transformations" is justified, this is the first time when their opponents are just as strong or stronger, so they need to step it up a level to proceed on their journey. This also means that their enemies ahead are also going to be this strong, so the formula that fights proceeded will change from this point on.
also, the mugiwaras have been sailing from island to island without much government interference. but now they have invaded government territory, but also declared war on the the world government. this also will change how they journey to each island. How will certain islands recieve the mugiwaras after this. Most people talk about higher bounties, but also notoreity(sp) will go up as well, they will not be as warmly recieved as they once were. THis also changes the one piece formula.
Im not sure how the buster call will affect how their notoreity(whether they will be blamed for the call like robin was, or everything that happened on the island will be erased)
anyways, what do you guys think will happen to one piece after this arc. I think oda wants us to see this as a turning point for the manga, what do you think will change?