Another thought just hit me, what if Kidd became an ally of the Blackbeard Pirates, while Law is an ally of the Strawhat Pirates? During the final war or w.e, Kidd is backing Teach with his own motives ofcourse (just like Kuzan and the rest of the Level 6 prisoners).
This would give Kidd some development, give BB more firepower, and not ruin Kidd's character further by making him a tsundere for Luffy.
Why does Oda have to be such a pussy?