$54-57k. I just can't see BMW raising the price in a huge way over the outgoing model (I think $10k is considered a "huge" jump in price). Plus I have a feeling that a lot of the equipment that's standard on the EU version(s) is going to be optional on the US version for 2 reasons:
a) it allows BMW to lower the base price and thus attract more possible customers.
b) given how much the car costs in countries such as the UK (over $100k US if I'm not mistaken) I think it'd be hard for them to justify the price without a lot of nice standard equipment.
I expect a well optioned model to be under $70k out the door.