You'd hope that EI will do nothing unilaterally.
How the deficit would divided up, should EI and the DAA (which other companies are involved?) is unclear.
Based on shareholders' funds, the DAA is a slightly larger company than Aer Lingus (952m v 835m), so it would be expected that their share would be slightly larger. Still, you aren't even looking close to 750m.
What is possible is that with the recent upturn in global stockmarkets, the level of the deficit may have declined. EI and the DAA may want to use this to create a once-off permanent solution.