The cool thing is since Thing's from another universe, he can still come back as Microchip. He won't, but still.
Jeff Snieder of theinsnieder is claiming he got a tip about Downey as Doom way back in May that also suggested he will indeed be introduced in the stinger of this film.
That reminds me of the Ultimate Universe where it was he was a space robot swarm named Gah-Lak-Tus. And that was dumb so right before Secret Wars actual Galactus showed up and wrecked shit.