I think it's a slight misconception that ALC 'moved' to SEN, as SEN operated before STN ceased. I think it was more to do with EZY removing based units, and the casualties included routes where there was direct competition with FR.
Nowadays aside from the blossoming relationship with MAG EZY seem more up for the fight with FR. So if this is true, the inclusion of ALC doesn't surprise me, more the end of summer start.
NCL is an interesting inclusion to the list given that NCL-LGW is also being launched