Sales-wise, the Micra outsold the Spark and the Mirage during its entire run here (cumulative/total sales). Though monthly sales dropped near the final year or so, and the Spark started selling more.
No parts are shared between the Micra/Mirage. Different cars.
Nissan Canada says they cancelled it because the next gen Micra, which has already been released in Europe, was going to be too expensive to compete in the entry level market here.
Which doesn't really make sense because the company's new "entry level" car is going to be the redesigned Versa sedan, which is going to cost a lot more money than the base Micra.