10. The Guardians Of The Galaxy Will Join In The Fun
Although this is pretty much guaranteed to happen, it hasn't been confirmed yet and so it has to be called a rumour at the current time. The Guardians of the Galaxy have already encountered Thanos in their titular movie earlier this year and they are sure to have their collective eyes on him. In fact, Drax the Destroyer - not content with defeating Ronin at the end of that movie - openly said that Thanos was next on his list. This makes sense, because Thanos will have been building up as the big bad for years by the time this movie comes around and, therefore, he will need to be presented as a massive threat - that he requires two teams of heroes to combat him will convey him as such.
