There's a break between when principal photography on the Marvel sequel Thor: The Dark World is expected to wrap and when shooting commences on Captain America: The Winter Soldier in March next year. Rumors that filming on Edgar Wright's Ant-Man could begin at that point circulated for a while, fueled by the impression that the superhero could hit the big screen before Avengers 2; however, Marvel has set Wright's project for a Fall 2015 release date instead.
Now, it appears that early 2013 slot is being set aside for Avengers writer/director Joss Whedon's S.H.I.E.L.D. television series, which we're hearing will begin filming as soon as next January.
S.H.I.E.L.D. is developing under Whedon's guidance, and he's working alongside his brother Jed Whedon and sister-in-law Maurissa Tancharoen; the trio previously collaborated on the Dr. Horrible's Sing-Along Blog mini-series and Dollhouse TV show, while the latter duo have also written for Starz' Spartacus. Whedon is planning to direct the pilot (which he's also co-writing), while Tancharoen and her husband are expected to assume the bulk of showrunning duties thereafter - once Joss starts to work full-time on the Avengers sequel, that is.
Variety's Marc Graser has the scoop on S.H.I.E.L.D. starting production in January 2013, so there should be several big casting announcements forthcoming over the next month. So far, Ming-Na Wen (SGU Stargate Universe, Eureka) is confirmed as one of the leads in the show. Meanwhile, Clark Gregg is prepped to reprise his fan-favorite role as Agent Phil Coulson, which is an announcement that has incited much speculation about where the series takes place in terms of the Marvel Cinematic Universe (MCU) timeline.
There are still three major character roles on the S.H.I.E.L.D. TV series that have yet to be filled (officially, that is), in addition to Wen as Agent Melinda May - who was previously-named as Agent Althea Rice, in character descriptions that were released not that long ago. However, MCU S.H.I.E.L.D. employees such as Agent Maria Hill (Cobie Smulders) and head Nick Fury (Samuel L. Jackson) are not going to be crossing-over into the show-verse; though, those two will be among the familiar faces that appear in the aforementioned Captain America sequel.
It sounds as though the S.H.I.E.L.D. TV show will be arriving on the small screen by the second half of 2013. We'll update with an official date once it's announced.
As for 'Phase 2' of the MCU: Iron Man 3 releases May 3rd, 2013, Thor: The Dark World on November 8th, 2013, Captain America: The Winter Soldier on April 4th, 2014, Guardians of the Galaxy on August 1st, 2014, The Avengers 2 on May 1st, 2015 and Ant-Man on November 6, 2015.