5. Thanos Will Appear (And So Will An Infinity Stone)
Now that Thanos has decided to get his own hands dirty rather than relying on underlings to collect up the Infinity Stones for him (an odd strategy that was never going to work in the first place) he's on a collision course with every character who he thinks (or knows) has a Stone in their possession. That means in Phase 3 he's going to be visiting the Guardians to retrieve the Power Stone, the Avengers to take Vision's head off, the Collector to retrieve the Aether, and Asgard to get the Tesseract. If he doesn't do the last thing on that list within a Thor movie, it will be a ridiculous left-field creative decision. The Evidence Thanos simply has to appear. If Marvel choose that to be no more than another cameo, it will be a mistake, but there's no way Ragnarok can happen without the Mad Titan playing some part in the narrative.
