I personally don't think she will go to Nascar. I think she's just using it as leverage to get a better deal with Rahal. She has said several times that she just dosen't want to run the long schedule like Nascar runs. She prefers the shorter schedule that they have in the IRL. She is bartering for 1) cars that can actually compete. Rahal Letterman is pathetic, and 2) possibly more money.
I could be wrong, and she may actually make the jump. Quite honestly, I have mixed feelings about the possibility of Danica running Nascar. The thing is though, Nascar is going to make her run at least 1 or 2 years in the truck or Busch series before she will be able to run in Nextel Cup. She's already in the elite series in open wheel, so it would actually be a step down, with no guarntee that she would ever make it to Cup.