One dealer in the UK mentioned to me earlier in the week that the M2 would be built in it's current guise between 2016 and 2017 (that'd make sense if it was getting a new engine in 2018). He said 400 units would be shipped each year.
Another dealer told me that the M2 would be built up until LCI in 2020. They didn't even know what a CSL was though
If there's no M2 GTS or CSL, a M2 with the S55 in 2018 would do but I've also read a post from Scott26 (who seems to be a man in the know) that BMW confirmed the M2 would be a springboard for some track variants.
The M2 safety car looks good - sounds awesome. Not sure about the rear wing though. Personally I'd prefer a rear spoiler similar to the E30 M3.