NotTheGuyYouKill
Member
They might be going for Lang so that they don't have three smart scientists. There was excellent chemistry between Stark and Banner in The Avengers. Throwing in a third guy could muddy the waters a bit. Or they could do Pym with a splash of Lang's personality. They haven't shied away from changing characters to suit the MCU.
Then again, they could throw Pym in, and watch his inferior complex spiral out of control when Banner and Stark ignore him all the time.