I don't think it's too insane to hope for more material next movie - after all, Strange's plan seemed to hinge on Tony surviving and all the original Avengers seem to be alive - plus it's a great starting point for fic.

Yes. Actually this whole movie was like a fic fodder XD. That damn flip phone that Tony carried around for two years but was never used. And Steve looked so angsty the whole time and calling Tony earth's best defender (I thought it was strongest, but it was best XD). It's so weird that there were good Stevetony moments when they didn't even share a single scene.