As the MCU has gone on, we've seen the evolution of the Iron Man armours. We've seen the prototype leading up to the classic red-and-gold. We've had the Mark 5 suitcase armour (with the colour scheme of the Silver Centurion.) We've had the various specialised "niche" armours with the Iron Legion. We've had the Hulkbuster. And we've had the Mark 46, the design of which is specifically based on the Bleeding Edge armour from the comics. So, what's next?
Not taking into account the various "one-off" or specialised amours (like one made completely of cold iron to fight elves,) or variants like stealth armours, IMO there are four "main" armours from the comics that we've yet to see any versions of in the MCU (not taking into account the Model 51 Prime armour, which sort of takes the whole MCU Autonomic Prehensile System to the next level.) The Black and Gold Model 42, designed to be modular, being able to swap out various load-outs on the fly. The Deep Space Model 45 which, considering the plot of Infinity Wars, is likely to make an appearance.
And the Model 50. The Endo-Sym armour used by the morally-inverted Superior Iron Man. We never really had the "Tony turns himself into a Technopath" part of the adaptation of the Extremis storyline in IM3, and I think the upcoming Infinity Wars is the perfect time to effectively merge it with the Superior Iron Man arc, which introduced Extremis 3.0, and adapt it to the MCU.
Think about it. The threat that Tony has known about for years is at Earth's doorstep. The threat he wanted a perfected version of Ultron to be ready for. But instead of being prepared for this, Thor and Banner went and got themselves kidnapped (after the latter ran off,) and Steve tore the Avengers apart and destroyed any possibility of trust between the two of them, to protect the murderer of Tony's parents.
Another attack by an alien army was inevitable, and most of the Avengers were more concerned about not losing the autonomy the world didn't initially object to granting them. Which they only got because they defended the world from the first version of the alien army. I mean, "Then we'll lose together, too." What kind of crap is that?
But who cares? Because for more than a year, before Rogers even defrosted, Tony Stark privatised World Peace. Back when he first started, he wasn't answering to any authority, but he was still accountable, to the American people if nothing else. Ultron was a mistake. He sees that now. Ironically, Steve was right about one thing. The safest hands are our own. Putting all that information and power in even a perfected Ultron programme would have been wrong. Because if Tony's life has taught him anything, it's that ultimately he can only trust himself. The only one he can trust with the power and responsibility is himself. And if he can't handle it, then he shouldn't be trying to share the burden with others that will inevitably either die or disappoint him. He should instead transform himself into someone who can shoulder the burden entirely.
A few years ago he said the Iron Man suit was a cocoon. It's time to make that a little more literal.