Not only was Agent Carter cancelled, but the Agents of SHIELD spinoff series, Marvel's Most Wanted, will not move forward on the network. The show was to star Adrianne Palicki and Nick Blood, reprising their Bobbi "Mockingbird" Morse and Lance Hunter characters. Bobbi and Lance left SHIELD as an obvious lead-up to the new series, and now one has to wonder if they'll find a way back under Agent Coulson's employ.
Chances are we'll see Peggy Carter again somehow, possibly in flashbacks as part of the MCU. Agents of SHIELD continues on with a fourth season picked up by ABC. Maybe they can clone Peggy and have her join the team?