Thomas Cook and Thomson are presented in the airport as well...
Hardly like Ryanair would be the only operator there catering for the needs of holiday traffic.
Further more:
easyJet flies to BHX from Belfast.
Germanwings from Hamburg and Tegel.
Turkish also comes in daily and advertises a lot inside the terminal.
None of the above cater for any holiday traffic at present in significant numbers.
If it would be up easyJet's street, would they not already have expanded into BHX in recent years when Ryanair operates full flights from there?
Rumours about Norwegian are always around.