Ryanair has called on the Government to act 'today' to implement a new system for international travel.
CEO Eddie Wilson says the green list is now a "big stop sign saying don't come into Ireland".
On Monday, the four countries on the current green list will be removed - meaning there will be no countries other than Northern Ireland where people arriving into the Republic won't have to self-isolate.
Meanwhile, European leaders will meet next week with a plan to sign-off on a new 'traffic light' system for travel.
It will see countries across Europe designated as green, orange/amber or red zones depending on the prevalence of coronavirus.
The Government here has said it will largely adopt the new system, although Transport Minister Eamon Ryan saying it may take some time to come into force.
However, Mr Wilson told The Pat Kenny Show that action is needed immediately.
He said: "We're now closed to everywhere in Europe.
"They can come up with a new system, or adopt the traffic light system in advance - then, when it's agreed at European level, adapt to that.
"I fear what happens on Monday is there's going to be a fudge, and we will be left with the existing system which has now closed all the countries in Europe."
'Crisis to crisis'
The Ryanair CEO suggested Ireland's quarantine regime hasn't worked since day one due to our 'porous border' with Northern Ireland.
On the Government's response, he argued: "They've just limped from crisis to crisis on this, and there's just no coherent policy on travel or freedom of movement.
"We don't just live in Ireland... we live in Ireland, in Europe."
The new EU system will include an allowance for restrictions on a regional basis - and Mr Wilson said the restrictions for Magaluf or Lanzarote shouldn't be the same as those for Madrid.
Mr Wilson said his airline would be the 'last one standing' if there was an 'apocalyptic' scenario for airlines.
He believes the industry will recover from next year, but there will be changes.
He said: "What's going to happen in this industry is capacity is going to shrink, and there will be less aircraft around.
"If that capacity goes, it will take a long time for that to come back."