Let's make some fun assumptions then. easyJet could offer 2 million passengers a year with the following destinations and frequencies:
GLA double daily
EDI double daily
BFS double daily
NCL double daily
INV 2 weekly
KEF 2 weekly
JER 3 weekly
BCN daily
FRA daily
TXL daily
PRG 4 weekly
MAD daily
CPH daily
GVA 3 weekly
ARL daily
FCO daily
LIN daily
VCE 4 weekly
I work that out at just over 2m pax assuming a 90% load factor and 320NEO 186 seats. (Better performance on the TORA and LDA) 4 or 5 aircraft could do this schedule.