UPDATE: Emily will feature a completely different moveset than Corvo and even though both will feature the same campaign, both will have different interactions with the people and environment. Switching characters during the campaign is not possible and there is a story reason for that.
Release will be Spring 2016Dishonored 2 just got announced. 2 different characters are available to play with: Corvo or Emily. You will be able to finish the game without killing anyone. Little else is know, besides it being available for current gen and PC.

Also, Dishonored Definitive Edition is coming this fall, with enhanced graphics.
Screens after the break