I like to think he put on lots of weight and looked about the size of a sumo wrestler, to Indy and his friends they now call him "Big Round!"
He dead. Gimme a break. Indy takes on a kid side kick for dangerous adventures and he ain't exactly training the dude like Batman does Robin. He probably died the very next scene after the credits rolled.
I like to imagine Short Round being the head of a crime syndicate or drug cartel, some Yakuza type stuff. Having took the tomb raiding knowledge from Indy to steal artifacts and propel himself into power after years of waiting for Indy to return but he never did.