Let me preface this by saying I am not close to Indy and have not seen them play much outside of the highlight reels and a little bit of last night's game...but I'm not sure if Rhodes was injured last night or not but Addai looked great. If Rhodes was healthy, and he shouldnt have been out there if he were not, then I would say Addai should take over right now. 20+ touches a game seems rather appropriate to me, 16-18 carries and 2+ catches should put him in line for roughly 100 total each game with a decent shot at a TD every week. That would make him a solid #2 RB.
If Addai isn't given the job next week he will before week 10. I don't own Rhodes but I think he sees 6-8 carries a game very soon and would move him to a team needing a RB ASAP. This might be the last time we see Rhodes with more carries than Addai.