It's going to be up top, not inside.
Mazda has been telling the press that it has a big announcement for the 2016 New York Auto Show. We know that this will be a world premier, but Mazda hasn't confirmed exactly what the big reveal will be. Rumors have been circulating that this could be the reveal of the hard-top version of the new MX-5. Autocar received an invite that Mazda sent out for the event which contained a folded piece of paper saying "Help us blow the lid off at the New York Auto Show." Remember the last-generation Miata got its hard top eight months after it first debuted.
The new ND Miata will likely get the same folding metal roof, with a slightly lighter and more compact mechanism that doesn't impede trunk space (like it had truck space to begin with). The hard-top Miata will likely be called the PRHT (Power Retractable Hard Top) in the US, or the Coupe in Europe. Hard-top Miatas made up more than 50% of sales in the US and over 80% in the UK. Some people may be disappointed that Mazda is adding a hard-top roof rather than a turbocharger. However, we think that for now, this is a good move, not saying we don't want a turbo Miata. Mazda's hard-tops are typically well-engineered and we think that the ND Miata will look great with a hard top roof.