Yea like Archy said, this was discussed in the manga section all the way back to when Ace died. Thats when the idea of an timeskip started to be speculated on. And once Luffy came to Amazon Lily and Rayleigh came and said he would train him everyone was 99% sure of it. Only reason it hasn't been discussed here is probably because most of the people in here are manga readers and they don't wanna make it seem like they spoil. One of the sad things is that things don't get discussed enough and not many predictions is thrown out there in the anime forum.