It would be a shame if the post-credit scenes don't relate to something, as it was the linking factor of the ones in the first movies (Ironman had Nick Fury introduced as the underlying link, Hulk had Ironman linked to it (Stark), Ironman 2 had Thor linked to it (hammer), Thor had Captain America linked to it (cube), Captain America linked to the Avengers (a trailer for that movie), and Avengers looked to have the Galactic Guardians linked to it (Thanos))... so it would be a shame if the post-credit scenes now are just random bits "sticky-taped" to the end. If there were another Hulk movie coming out soon, it would have made sense like the clues from the first movies... but meh.

I had never actually heard of the Mandarin before this movie, so had to do some reading up on it... and I agree, this movie should have just not used the name of the character if the writer/director didn't like the Asian connotation to the original character. It would be like Michael Bay using the character name of Megatron in the first movie as the name of the boombox Decepticon (Frenzy).
He could have still used the character fully without worrying about offending anyone... The original character was created in a time when racial stereotypes for criminal characters was common because all the western propaganda during the cold war era made the unknown scary to the masses. Look at Star Trek, created in the 1960s at the height of the Cold War - Romulans/Russians were originally the militaristic main foe of the Federation/USA, while the Klingons/Chinese were the savage barbarians. (although, by the time the Soviet Union collapsed, the Klingons had become the fan-favourite race, so ended up being used as part of the "USSR collapse" metaphor in Star Trek 6)

I hope that if there is another Iron Man movie, they might consider using the real Mandarin, if one exists, and his ten rings... because an origin story (of where the Rings came from) and being able to be virtually unbeatable with them would make it a decent challenge in a full-length movie.