Keep in mind that 'Aer Lingus' is just one brand under the umbrella of IAG. If it is necessary at some point to redeploy their assets back to Eire, IAG has alternative options to cover capacity at MAN. And there are three compelling reasons why this should be of interest to them: firstly, the collapse of Thomas Cook has removed upto six high-capacity A332 departures per day between MAN and destinations in the Americas (including the Caribbean and Mexico); secondly, the main US carriers have stepped away from the MAN market for now, barring Delta who retain exposure via Virgin Atlantic; thirdly, IAG will not be minded to afford rival Virgin Atlantic a free run at the proven Transatlantic market from the North of England.
Of course, the big imponderable is the course of C-19 restrictions ... but that is true generally, not just for MAN. What does offer hope is the successful rollouts of vaccination programmes in both the UK and the US. This offers the possibility that markets between the two could actually open up sooner than those between the UK and some Continental European jurisdictions. Of course, we then need to see what experience the Florida vacation market can offer: how much capacity will socially-distanced theme parks be able to accommodate? Will restaurant space be freely available for walk-in trade? Presumably ex-Florida cruising will be very limited for a while yet. New York City / Shopping breaks will be attractive to many ... again, provided that C-19 restrictions are not too onerous. And in addition to the leisure sector which is so dominant from MAN, there is still a worthwhile tranche of business travel and cargo to go after as well. Plus VFR, of course.
So, C-19 rules permitting, entering the MAN - North America market is not a huge gamble for IAG / Aer Lingus. Their capacity will be much less than that previously provided by Thomas Cook ... and remember that their Transatlantic routes were highly successful ... TCG was brought down by accrued debts elsewhere in their nebulous empire. Meanwhile, they're primarily up against a significantly-downsized Virgin Atlantic which has retired its high-capacity B744's and reduced destinations and frequencies. TUI's presence essentially relates to niche in-house package holiday options, and all the US carriers have dropped out for now. So if C-19 restrictions are lifted, Aer Lingus will find themselves as one of the big(-ish) two in a sellers' market. Demand for travel is not in doubt ... only permission to do so is. Not a bad place to be. And if C-19 does thwart everything, then that is a concern which will extend well beyond the MAN market. Dublin and London departures will be similarly impacted.