According to our flock of camera-toting spies at the Nürburgring, the next Miata is likely to grow a bit, as new models are wont to do. In particular, it will be longer and wider, and the wheelbase is likely going to be stretched, based on the shape of the wheel wells and doors. Both of those factors will add more space in the cabin.
Those are the big indications provided by these photos, but while the MX-5 might be growing, it's a safe bet based on these images that it, and the (likely pricier) Alfa, will retain the classic, long-hood, short-deck styling that so typifies rear-drive roadsters.
With testing still in the earliest of stages, it's not clear when the MX-5 will arrive on the market, as Mazda has kept that intel locked up as tight as possible. As always, as soon as more info is available, you'll be able to read it here.