Now? Simply put what all work Nokia have build in Qt, Symbian Foundation and MeeGo. No, it's not possible.

From the start if they would have jumped to Android they would be in better position than now, but i believe Nokia could have never been able to repeat the Symbian success using Android.
With MeeGo, Symbian Foundation and S40 they again got something unique and with Nokia brand they are one of the couple of brands in the industry that can make this turn to something big. Time is running, but imho it's possible.