This is entirely rumour, ok...
On another forum, the DUB forum, someone has just posted that there are rumours circulating that Aer Lingus has/will oder/ed 10 Airbus A350 and will be announed before Christmas.
To be honest, I would have been surprised to see EI return to Boeing (don't flame me, just a personal 'hunch'... no more).
This rumour may well be true. Manion, EI's new CEO is putting many of his efforts into expanding EI eastwards, and said shortly after joining EI that he would announce new long-haul routes to the east and new long-haul aircraft.