That's left to be seen, but I highly doubt that it will ever happen. Since 2005 and up to the release of MGS 4 last year, there was a lot of press coverage and hype surrounding the game. After all, MGS 4 brought an end to Solid Snake, who had been the main protagonist for the Metal Gear franchise for over 20 years. It was practically the end of an entire videogame era (so to speak).
I doubt that Raiden will draw as many players as Snake did, irregardless to the fact that "Rising" being a multi-platform release. Also, don't forget that "Rising" is just a side-story, and unlike MGS 4, Kojima will not be directly involved in the development for "Rising" (that will be left to a new director, and a new team).