The timing of this news -- five days before the start of the annual Comic-Con International in San Diego -- is conspicuous, but given that Marvel Studios has two earlier release dates on its schedule reserved for films that also haven't yet been officially revealed, it's likely too early for an announcement on these new dates at that show. Perhaps a more probable candidate is Disney's next D23 Expo, set for August 2015.
Here's the current Marvel Studios release schedule as it stands -- lots of question marks, though a "Doctor Strange" film is in development and has a director (Scott Derrickson), and third rounds for "Avengers" and "Thor" are safe bets to take a couple of those slots.
Aug. 1, 2014: "Guardians of the Galaxy"
May 2, 2015: "Avengers: Age of Ultron"
July 17, 2015: "Ant-Man"
May 6, 2016: "Captain America 3" [not official title]
July 8, 2016: Untitled film
May 5, 2017: Untitled film
July 28, 2017: Untitled film
November 3, 2017: Untitled film
July 6, 2018: Untitled film
November 2, 2018: Untitled film
May 3, 2019: Untitled film