Lol, thanks.
I wonder if Luffy will actually defeat all the Yonkous. It seems like Big Mom is really hating this guy, but we still have the Lola card. Now, your end is possible, yet there are some stuff missing. Personally, ending Shanks with Blackbeard just to give Luffy the time to go to Raftel is not a very fulfilling ending for a character as big as Shanks. Now I'll give you one thing to think about:
Shanks traveled with Rodger to the end of the Grandline, I assume. The other option is that only a select few members of the Rodger Pirates actually made the last leg of the journey, while the others stayed behind. (Something to do with destiny?) Or maybe Shanks was purposedly left behind so that he could find One Piece on his own, with his own crew (like other young pirates (Buggy)), and only the old members of the crew made the final journey. In that case, Shanks went back to find a crew and then made it to the New World and is now trying to find One Piece. He doesn't seem very suspicious, and he is pretty laid back, the chances are that he is keeping a secret of some sorts.
On the other hand, he might have traveled to the end of the Grand Line, and is now waiting for something to happen. Rayleigh said they found the truth, but did not have the skills to understand it, or couldn't do something about it. Luffy is on the path to discover it, and so Shanks is waiting for him.
Maybe Shanks will be the guide for Luffy to either find Raftel or after he finds it, to pursue the truth. As such, Shanks role is not only to be an inspiration for Luffy, but to also be a guidance, linked with the void century.
Having Luffy put the hat on Shanks grave and then disband the Straw Hat Pirates is good though. But I wonder, what if it's someone else's grave? Possible suspects:
- Garp
- Dragon
- Rodger
- Rayleigh
- Luffy's Mom (assuming she might have a greater role in the future)