As funny as it would be if Luffy got the Kidd treatment after all the buildup, I think Luffy will just keep on fighting with a wound. I don't really think there's an alternative, since Imu doesn't seem like he's in a rush like Crocodile was when he stabbed Luffy, so either he kills Luffy, or Luffy keeps fighting for a few chapters.
I don't think either Loki or Gunko would really work as stall devices at this point, and Zoro/Sanji are busy, so unless we're about to get the craziest Jinbei upscale of all time....
The best case scenario is that Imu did actually low diff Luffy, but he fucks around for a few chapters before getting taken out by a plot device....which is just so disappointing after 10 years of buildup.