Can Dr. Doom defeat Thanos and will he be featured in an Avengers movie?
Generally, no. Dr. Doom is extremely powerful, especially with his suit that allows him to absorb energy, but he's fairly inconsistent with his power. Generally he loses to the Fantastic Four, but higher end showings have him surviving a blast Infinity Gauntlet's Power Gem
Thanos with the gauntlet and the stones? No, he really doesn't stand a chance.
Dr. Doom with the gauntlet and the stones? He'd destroy Thanos with a thought.
Both of them without the gauntlet and stones... It would be a knock down fight but I think Thanos would have the edge. Depends on if Doom has time to come up with some magic or weapon, then he'd have the advantage.