10 Ways To Get The Fantastic 4 Into The MCU (That Wouldn't Suck)
4. Use Alternative Dimension Reed Richardses
For whatever reason, Marvel really loved Reed Richards back in the day. For proof of this, look to the Council of Reeds, a collection of Reed Richardses from across dozens of dimensions who gathered to be clever together.
The Council set themselves up as protectors of the all universes by averting cosmic disasters and making the multiverse a better place. The Council had a hell of a God complex and Reed Richards from Earth-616 (the main Marvel continuity, try to keep up) couldn't join them as it would have meant giving up Earth-616 and his friends and family.
The Council's position as self-appointed cosmic troubleshooters means they could turn up anywhere, especially in the adventures of cosmic-themed heroes like Doctor Strange and the Guardians of the Galaxy.
Most tellingly for the MCU, several Reeds have acquired their universe's Infinity Gauntlet, making them the perfect way to tell the MCU how powerful the gauntlet and its gems are, and what happens if the wrong person (or, indeed, anyone) gets hold of the whole set.