Prediction by Ryan
As we all know this is the part where we learn about Luffy's past, on how the bond of the brothers (Luffy and Ace) are made ... the flash back may continue to about 2-4 more chapters until Ace sees Luffy as a little brother and until he promises will not die no matter what (Chapter 574-The death of Portgaz D Ace). This might end when Ace first leaves Fuchia Village, and we may see some notable events of Luffy before he too leaves Fuschia Village.
After the flashback Luffy will train with the help of Boa and Jimbei. Law will not help in training but will assist in keeping Luffy Healthy and treating his wounds. I think he will leave when Luffy has fully recovered.
I really don't like the idea of a time skip, but the time skip will happen, but I don't think it will be a 2 year like time skip, I'm betting that it will be more like 2-4 week time skip. That will be for Luffy's training and recovery, and will allow us to follow up on the other Strawhats and see how they've done (I really want to see them especially Zoro). From the day the crew is seperated until the two weeks stay of Luffy on Amazon Lily, this will be the time Interval the other crew members had done, and the other two weeks is the reunion of the crew (except Luffy).
Oda might show how the other members of the crew trained, showing the results of their training would most likley be demonstrated in future battles.
During the last two weeks of Luffy's training, I think Zoro will find the other Strawhats with the help of Perona, I would really like to see that happen, mostly because Zoro has poor sense of direction. But what I would really like to see is Zoro lead the Strawhat crew in finding their captain, then there will be battles for information of Luffy's whereabouts, and the one who will supply the information will probably be Law.
When they find Luffy the ship should already be coated, and with Franky's visit to Vegapunk's home he might have upgraded the Sunny Go a little making already to go to Fishman island, and the one to guide them is Jimbei.
And also I don't think Mr.2 will join up with Luffy's crew. He is more likley to be back with Crocodile because Crocodile sees some use for Mr.2's ability, or he may join Buggy because of the relationship the two built when they escaped Impel down.
I don't think Jimbei will join, he may guide them to fishman island, but I think he will be stuck on fishman island for some reasons.
I would really like Boa to join Luffy's crew, but with the way things are I doubt that will happen, I think the shichibukai title will be the biggest issue.
I doubt Oda will add another crew to the strawhats, I think he planned for the crew to be small, but in lack of numbers, Luffy will have fleets of allies much like Whitebeard did to help him when he needs it.