Well, the Blackpool to Hazel Grove services cannot become 6-car. Although the Hazel Grove platforms are plenty long enough, the layover sidings are only 121m, 5-car maximum. Although the original plan was for the Blackpool services to go to Macclesfield, where 6 cars could be accommodated, not Hazel Grove. Maybe the better performance of the 331 vice the 319 might make this route feasible?
Also I think that, after the December timetable change, the Blackpool to Airport 331 will have to be stacked on top of the Liverpool to Airport 195 in the same Airport platform, meaning neither can be longer than 4-car. Unless one of these services terminates at Wilmslow intead of the Airport.