this is highly unlikely. this is essentially saying, "oda has put a major character in a position for no reason." writing 101 - nothing is done without purpose. the idea that law would have no role in this fight also belies the fact that this fight is the entire point of the Straw Heart alliance formed on punk hazard. in fact, you could argue that oda introduced gamma knife vs. doflamingo expressly to set up internal damage which has become crucial to this current fight. oda would have to be a pretty inept writer to have an alliance building for hundreds of chapters and provide no pay off.
strategically, you don't get rid of the paddle in your boat if it leaves you stranded up the stream with no way home. doflamingo is the paddle in this case. oda got rid of him early, so there's some other story piece that has taken his place. in my opinion, it's the fact that this battle is no longer just about toppling a yonko, but also serves as a fight with One Piece, the poneglyphs, and Pirate King title on the line. this means Kid, Law, and Luffy should be the premier fighters when you consider what the fight represents.