We all know that Iron Man is a powerful Avenger but just how powerful ?
In the first Avenger film Thor kindly boost his suit by 400% so I'm saying what if Tony Stark manage to store that power away for a rainy day ( ie bigger invasion ) so that being said I believe Tony to be the next Thor if he play his cards right. Meaning his new best friend will be Thor as Tony will trick him in helping him create a suit powerful enough to battle in the Infinity wars and powerful enough to hold all the gems
In the second Avengers film, he created Ultron to fight the wars when the Avengers can`t. The result wasn`t the one he has hope but the vision he was shown by Scarlett Witch did infact encourage him to create a suit more powerful than anything he has created before and perhaps powerful enough to hold all the gems and be a force to be reckon with.