It will take a hit as ty are turned in for the new M3. Same thing happened with the E46M3, same thing happened to the E39 M5. I bought my '03 M5 in 2005 before the E60 M5's came out and the market was flooded when the new car came out, and even though the prices had already taken a major depreciation hit in the 1st two years, it to another hit when the new model came out.
I say buy it, drive it and enjoy it. It's not an investment, and it will be worth MUCH less whenever you decide to sell it.
Current: '13 E92 M3 Euro Delivery
Wife's: E36 M3
Gone: E86 M Coupe; E30 M3, E39 M5