They'd be happy I think. Flying around with one-third of the passenger load but all tickets sold saves a lot of fuel... Also, they can adjust fees as they like and introduce new ones as they see fit - "want a second&/third seat just for yourself - that'd be an extra $20 'superwide seat' fee"., then waive this fee for CoS and passengers with service animals upon qualification.
Air New Zealand monetizes empty seats already: https://www.airnewzealand.co.nz/buy-...at-at-check-in