It would be easiest way for them to make money. If they remade 1-6 before making episode 7 then they would have less work to do on design and story for those 6, and they could try to please more people by improving episodes 1-3, they could try to keep episodes 4-6 true to the originals, and bring new viewers in from the very beginning instead of part way through a series. They could also use the actors to play characters throughout and not have to cast younger or older versions of the characters each time. They would even have their logo on the whole series and not have to worry about Fox getting a little share of 'their' money every time someone buys the existing movies. It will happen eventually, they could just pause to plan it out and try to get it perfect before rushing into making a new film.