It's an ambitious bet. Even Barnett himself described it as "bullish." Time will tell if another word -- similar to that one but with a relocated "i" and an added "t" -- will be more appropriate. If all 1.5 million shipped retail boxes sell and there's close to 100% player retention after the first month (that last bit is very unlikely), the game will quickly be halfway to the end goal. But we know from past experience that significant attrition can be a problem.
The interview is full of other cocky statements, about World of Warcraft and other topics. If you're interested, grab yourself a grain of salt and start reading!