So we all now know that at one point Gol D Roger was the owner of the straw hat. He then went on to become the Pirate King. Also. Luffy being the main character and all. We just know that once One piece ends in like year 2020 he will finally be the Pirate King. This means both Gold D Roger and Monkey D Luffy will have been the Pirate King. And the similarity they share is their personality ETC and of course.. THE STRAW HAT!
Now the main topic I want to discuss here is. Gol D Roger obviously gave his hat to Shanks because of many possible and same reasons Shanks gave it to luffy. He see's himself in Shanks. Or see's potential. Stuff like that. Gol D Roger obviously made the right choice giving it to Shanks because look where he is now! He is a Yonko! So do you guys think Shanks will become the Pirate King first? And then it might be an epic battle between SH crew and Red Haired crew? Gimme your thoughts!
I personally believe this: As the story progresses. I believe Shanks will indeed find one piece or more possibly just be considered the strongest crew in the world and Luffy will be shattered to find out that he lost. Of course since Shanks is Luffy's Idol Luffy will shake it off and say somthing like, "Well if I was going to lose to somebody I am happy it was to Shanks". Luffy and his crew will then carry on with their adventures until the point comes where they battle each other (In a friendly battle.. No killing) for the title of Pirate King! I believe that this way people will truly believe that Luffy is the TRUE Pirate King since the world will know that the SH Crew defeated the strongest crew in the world (Which is Red Haired). If Luffy were to just find one piece and become the Pirate King.. People will call it a fluke or something. This way they will prove themselves and nobody will question this title. HOWEVER! It's not over yet. Everyone says shanks will die. And I somewhat agree. Not against luffy though. Definetly not. 0% chance of that. Shanks will be captured and then the pirate king will save him ;)
So my conclusion is.. WHOEVER POSSESES/POSSESED THE STRAW HAT WILL BE PIRATE KING!! WOO!