The latest hint towards the unveiling of the Spider comes from FCA's own blog. In a story about the first customer deliveries of the 4C Launch Edition, the last sentences nearly let the cat out of the bag: "Alfa Romeo plans to introduce eight new models by 2018. You'll get your next Alfa fix at the North American International Auto Show in Detroit in January."
Just looking at the roofline of the 4C, it's pretty clear that a convertible was in the cards from the very beginning. Alfa confirmed that with the Spider concept (pictured below) at the 2014 Geneva Motor Show, and reaffirmed the drop top in the company's five-year plan.
Further evidence for the fast approaching debut came recently when a fully production-spec 4C Spider (pictured above) was spotted being professionally filmed in Spain. It sported some changes over the concept, including a cooling inlet on the driver's side rear fender and exhausts at the corners, instead of the center.