Well, they already fly to Réunion, San Francisco, Tahiti and the Dominican Republic and seem to be surviving. However, at the moment, they only have a fleet of three planes but with three other planes on order.
All of these little airlines try really hard. French Bee doubled the number of passengers from 168,000 in 2017 to 350,000 passengers in 2018. But it just takes one little incident removing a plane from service to make the whole system collapse. Therefore I would only buy a ticket on such an airline if I had full travel insurance.