I can see maybe mentioning them more but in their solo series (comics) they don't usually get help from the other Avengers. This isn't going to be that much different.
I don't need the other avenger to show up but at least reference them. That's all I ask and that's what they did in all the phase 1 films. Rhodes even asked tony about they avengers so they had the opportunity to add some lines saying thor, cap and banner are off dealing with other things and that shield went undercover/silent after events of Avengers. Anything is better then nothing. What was the point of tying all the stuff together in the phase 1 films, only to ignore it. Seems like they are destroying what they tried so hard to create.