In Marvel cartoon X-men Evolution there's the team of Mystique called The Brotherhood. Mystique is the leader of the team and has recruited several well known mutant like Avalanche, Toad, Blob, Spyke, Quicksilver and Scarlet witch. Coincidence, i don't think, because in the end credit of X-men: DoFP, it shows Mystique recruiting some mutants which include Toad and Spyke. Toad is one of the official member of The Brotherhood and Mystique also. If Marvel is picking ideas from the cartoon ' X-men Evolution' then where is Quicksilver and Scarlet Witch. Marvel has send them to be in the Avengers 2: Age of Ultron. Why? The reason why they must be in X-men universe and not in The Avengers, is because they are the children of Magneto, Eric Lehnsherr and official members of The Brotherhood.
This brings me to think that Marvel is planning to bring up together The Avengers and The X-Men universe. Another relationship between these two universe could be the third episode of X-men evolution season four.
The destruction of The H.Y.D.R.A by Wolverine and agent X-23 could be a scenario for Wolverine third stand alone movie.