@Lao:
I'll try to argue with you on this one. Wouldn't it be dissapointing if Luffy will not defeat Doflamingo? All this arc was set up for him to kick his ass, and you think that he will not do it? I see kinda Crocodile vs Luffy situation, when Luffy lost 2 times but the 3 was a winner. And it's already time for Luffy to beat someone of this caliber, or otherwise the timeskip have been in vain. We still haven't seen what Luffy's fully capable of. We still haven't seen what Doflamingo is capable of. Same goes for Zoro vs Pica situation. Also this is One Piece, if Luffy says "I'll kick his ass" he will do it (not counting his encounter with Magellan), so I just don't understand why you think Luffy will not beat him.
Fujitora stated that he will take care of Doflamingo, but that doesn't mean there will be an all out Dofla vs Fuji fight. It simply may mean, that afte Doflamingo is sent flying Fujitora will say something like: "With the title given to me by Marine HQ I hereby strip you of your Shichibukai title" kind of what Tashigi did at the end of Alabasta.
P.S I think considering Zoro can't defeat Pica is pointless, until we see an actual Pica fight.
Sorry for the late response, but I don't think it would be disappointing if we don't see Luffy defeating Doflamingo. While I could see Luffy having the passion to want to defeat Doflamingo, we have to consider that the fact that Doflamingo isn't just some run of the mill villain, but a very serious threat that even Aokiji had expressed earlier to Smoker. Sure I can see the parallel's between Doflamingo and Crocodile, but even Doflamingo stated that he wouldn't underestimate Luffy, and even though he sort of has done the opposite, when it does come time for a fight, Doflamingo will not just leave Luffy "defeated and dead" as Crocodile did. In by no means do I think Luffy will be tossed around like a poor little puppy either. I really do think they'll match up rather nicely, but this will be the first time Luffy has gone after a top tiered fighter since the time-skip. He has the ambition and the will to fight, which matters the most. He will gain battle experience, and know what it is like to fight a top-tiered fighter, but will not be the one to defeat Doflamingo, as I don't think he's capable just yet to win against such a foe. I mean, we're talking about a fight that, if evenly fought should take a long, long time to defeat. Doflamingo has the nerve to even kick Fujitora as was seen last chapter. He's perfectly capable of fighting an Admiral if he needs to, and to have such courage and ambition is not to be taken lightly. And what matters most I think in the scenario that I have in mind, is if Doflamingo is weakened in a fight, or exhausted to an extent in a fight against Luffy, then Fujitora can take down Doflamingo with greater ease. And Fujitora will want to take down Doflamingo on his own, due to his own ambition but more so from what he'll learn once Sugar is taken down and the citizens will most likely revolt and express their 10 year long struggle under Doflamingo's rule. And this will earn at least for the time Luffy has on the island of Dresrosa, to roam free without having to deal with the Marines. Don't get me wrong, I'd love it if Luffy actually does happen to defeat Doflamingo, but I do believe it's perfectly possible that Luffy won't be able to complete such a task and it wouldn't bother me either. But Luffy also has to take Law back and get some aid.