They do seem to be taking the customer rather for granted here. I regularly travel on the routes down to the Canaries, often in Club, and whilst the passenger has the choice of travelling charter already, the aircraft are fairly full both in economy and Club.
People are willing to pay a little extra for hot meals drinks and space and the lower hassle factor of a scheduled flight.
To say that these will become Easyjet flights and passengers will be transferred does seem to be assuming a lot, The Club passengers will almost certainly be looking elsewhere, and with 25 per flight paying £300-£400 return that is going to make a dent in the balance sheet.
Many of their Mediterranean destinations such as Faro or Cyprus fit in the same profile, with the slightly more up-market traveller rather than the cheap and cheerfull stag party outing.
I suppose time will tell whether they want the routes or just the slots, at that price they seem to be getting a bargain.