Last i heard, Platinum did not seem interested in making a MGR2, so if you ask me, i'd give a huge chance it's not MGR2 that was teased, some chance if it was teased it won't be Platinum games, a slight chance it's Platinum Games changing their minds.
http://www.videogamer.com/xbox360/metal_gear_solid_rising/news/kojima_wants_metal_gear_rising_2_to_star_cyborg_ninja_gray_fox.html