It wasn’t clear if Dark Souls 3 was going to be developed for PC, or not. Not until this years E3 convention at least.
Dark Souls 3 is definitely coming out for PC, and will use Steam as a platform (who would have guessed?).
Although the announcement trailer doesn’t give us much to go on, you can only assume that DS3 will be full of the same dark, gritty story telling as seen in past Dark Souls installments.
It is set to drop on December 31st, 2015, and will be released on all major systems, including PC.