Sony is a company that has the phrase "We don't comment on rumors" on quick-draw, so obviously there isn't a lot to go on here. But, Hirai did at least leave open the possibility that the company could make Windows Phone devices or maybe even a Windows tablet in the future. Hirai made it clear that Sony's PC days were done and that the company would be focusing on smartphones and tablets, but said about Windows, "Microsoft has various OSes, including mobile. So, as Sony, we will consider new product development going forward."
There have been rumors recently about Sony working on a Windows Phone device, and those rumors make Hirai's comment about as close to an admission of a Sony Windows Phone as you're likely to get from the company until such a device is officially announced.