When people ask these questions...what I really want to say is; "Who cares?" But I usually say something a bit more diplomatic like; "Train relentlessly and see where it takes you." Sure it's fun...and sometimes quite effective...to imagine outcomes. But the only way to find out how good you can be at something is to consistently concentrate on it...work at it...train...and see then what happens. I feel it's best to quit worrying about the future...stay more focused in the present...and just keep taking the next obvious step.
This article does a brilliant job of describing how goal-setting can actually work against you and why many successful people do not set goals. It goes against the prevailing sentiments...but I feel it offers an interesting and liberating perspective. It's worth a look.