Platinum Games may give players a chance to put down Raiden's sword in Metal Gear Rising: Revengeance. Around the 2:48 mark in the Game Trailers E3 interview above, Platinum producer Yuji Korekado (through his translator) suggests the possibility of other playable characters.
Specifically, Korekado mentions DLC, which he confirms the studio is planning for post-launch. "Right now we don't have any plans for online competitive play; however, we do have some plans for download content for after the release of the game, that will maybe let you play as a different character or experience different types of missions." We sincerely hope the character is Old Snake and the mission is to do some skateboarding.