We'd be talking about the next generation arcitecture, so a RWD switch would be reasonable. Just speculation at this point but it just seems to make sense with them going to a straight 6. While they have been used with FWD arcitecture, it's just not typical.
That presentation, on other pages, talks about Mazda's strategy for the next 100 years. While that is a rather long time horizon, their immediate goal for the next 15 years is to greatly increase the average selling price of their cars. In that light, a switch to a more "premium" drivetrain layout (front engine, inline 6, RWD) makes complete sense.
I hope they pull it off. Mazda has always made nice driving cars. A RWD Mazda sure sounds nice...