I can't believe all the people here whining that it won't be an I6. The M3 started with a four cylinder!
Cars (even M cars) have gotten so big and so complicated, it's ridiculous. Two of the most fun cars I ever owned were a 1979 Rabbit and a 1st gen MR2.
Neither car was "fast". Quite to the contrary, they were both horribly slow, but both had manual steering and weighed over 1000 lbs less than any M car you can currently buy. The Rabbit in particular was really something else. The MR2 was great, with it's mid-engine layout, but I always felt like it was going to kill me (snap oversteer). The Rabbit could be tossed around like a beach ball. So much fun.
The original M3 used an I4 because that engine made the most sense. When the M3 moved to an I6, there were plenty of people who were disappointed. While an I6 has perfect balance, it's one of the least space/weight efficient engine designs. Don't get me wrong, I love an I6, and the trade off in space/weight is an easy thing to get past, but when you *really* want small and light, it's hard to justify.
I really do hope BMW goes with the "light is right" philosophy with the M2. It could very well make the M2 the most pure M-car since the 1M. If you wan an I6, by an M3. If you want a V8, step up and buy an M5, or go buy yourself a Boss Mustang or Camero SS.
His: 2013 ///M3 - Interlagos Blue Black M-DCT
Hers: 2013 X3 28i - N20 Mineral Silver / Sand Beige / Premium, Tech
Past: 2010 135i - TiAg Coral Red 6MT ///M-Sport