That would be one hell of a writing.
Yeah, it would.
And potentially it would give us a confrontation between WG, Blackbeard, Straw Hats and Revolutionary, something that can lead to the final stage:
-Teach's rush to Laugh Tale, to power
-he WG will consider him the greatest threat ever existed
-finally Luffy will meet not simply his father but the one who is willing to beat the crap out of the big evils they both targeted (WG, Celestial Dragon, CP0, Sabo stuff)
-Luffy crew and fleet will acknowledge their role in history, will take back Robin, beat Teach and go to Laugh Tale with Robin (and the legacy of O'Hara)
-The King of pirates, what remains of a New World without Yonkou, the Revolutionary army will go to war against the Celestial Dragons and Imu
Thanks, Rolling Ehichiiro Oda Nut