Nokia making an Android phone would probably be a terrible idea, honestly. Samsung has close to 50% of Android's marketshare. Motorola, HTC, and LG pick up most of the remaining 50%, leaving only small amounts to other OEMs. Trying to push Android would likely be more of an uphill battle than pushing Windows Phone has been.
Windows Phone is gaining marketshare slowly. It has broken 10% in some countries, and is pushing towards 10% of sales (not marketshare yet) in America. Nokia currently accounts for 80% of Windows Phone shipments, with HTC coming in at around 15%. Moving to Android would probably further marginalize Nokia's share of the smartphone market, as well as make them lose funding from Microsoft.
Given Nokia is responsible for 80% of Windows Phone sales, that puts Nokia at shipping about 5% of the world's smartphones in Q1. A far cry from Samsung or Apple, but it could certainly be worse.