I strongly doubt the prices will go up much, particularly for the M3 which is already an expensive car for the US market and doesn't change much from 08 to 09.
Probably a 1% to 2% increase on some key updated options (i.e. new iDrive) and that's it. The M3s are not selling that well and jacking up the price would not help in the US market that is so important for the M cars. I would expect maybe something like $500 increase for the updated regular E90.
The main point here is that BMW wants to encourage people to finance rather than lease. Consequently they will probably make the leasing terms a lot less appealing and encourage financing by keeping the prices somewhat where they are and offering lower rates.
We know that most people (about 60% according to BMW) can only afford BMWs because they are leasing them. I am assuming that the 40K less cars this year will come from these people.
Current: 2016 F80 M3 SO | AB XT1 | ZCP | etc.
Previous: 2009 E90 M3