In Avengers 2 the Avengers should fucking get their asses kicked at the end. Have a real downer of an ending, with the Avengers beaten/broken. Hulk banished. Earth conquered/enslaved, Cap reluctantly working for whatever force has taken over earth. Tony Stark critically wounded and near death, Thor returning to Asgard to find Loki on the throne. Think Empire Strikes Back ending but WAY worse. Then the final films for each of them (IM4, Cap 3, Thor 3, Hulk 2) should involve each of them getting/building/discovering their ultimate mojo-mcguffin, leading into an Avengers 3 two hour long climactic battlegasm.