Whilst not officially confirmed at this stage, recent comments from Joss Whedon and Kevin Feige have strongly hinted that Scarlet Witch and Quicksilver will feature in The Avengers 2. And as far back as last year Feige said that there's an arrangement in place for the use of the characters, providing their lineage isn't brought up.
With the rumors of their presence well established, attention is now turning to who would play them in the new movie,. and some information appears to have been released that would indicate that Marvel is favouring Saoirse Ronan for the role of Scarlet Witch. The studio is apparently looking to depict the characters as British rather than Eastern European.
Ronan is a fantastic actress who has demonstrated her action credentials in Joe Wright's rather excellent Hanna, so she certainly seems a good choice for the role. Appreciating that it's merely a rumour at this stage and might not actually happen, it's still a positive sign for the casting of the character. With this rumour released now, we would suspect rumours for the casting of Quicksilver to follow shortly.
More news on The Avengers 2 when it's available