First, we saw in Avengers: Infinity War Tony Stark is stuck on Titan (Home planet of Thanos) and then in Endgame first trailer he is floating in space with no supplies left and oxygen will be run out soon. He has only a few hours to be rescued, even after his rescue in Endgame we are pretty much sure that this will be his last MCU movie and we will not see him as Ironman. Even if we see him in any form or cameo in future MCU that will be very different.

So how Ironman can be a part of MCU after Endgame and here comes a theory that point directly to a comic. In the comic where Tony Stark disappears suddenly from the universe, we see him as an AI. The AI guides Riri Williams who afterward become Ironheart. In comic Riri is a genius teenager girl who creates own Ironman armor.

Because it is not possible to show Riri in current MCU the theory is something can happen similar to comic and we will see Ironman as an AI but here the AI will guide and mentor Spiderman instead of Ironheart. Here in current MCU Ironman became a father-figure to Spiderman who was guiding and mentoring him until Avengers: Endgame. Because Spiderman is going to be an important part of future MCU it is likely that someone like Ironman will guide and mentor him.