My day job is actually with an airline, so I know an awful lot more about this than, and the challenges ahead, than i want to.
The State will provide PSO funding to routes deemed essential to the states interest (Kerry - Dublin, Donegal - Dublin and Connemara - Arann Islands are the only PSO routes at the moment), and have to be tendered.
The new ferry PSO routes are different, in that the funding is short term, and to maintain supply chains.
Douglas and France are seasonal passenger orientated routes, that carry a lot of traffic outbound from Ireland. If there was funding needed to support them in the summer, that is a matter for the Manx and French governments more than the Irish government, and there are very strict rules about state aid.
What the state, ports and tourism bodies may do is offer loans with favorable terms to try help operators through what will really be a difficult summer (and into next year) no matter what happens.
The other thing is a lot of bookings for holidays will have been made at this stage, so the companies will have cash in the bank, it comes down how they manage the customers (if they can get people to accept voucher, short term that preserves cash flow).