MAN-DUB is one of Ryanairs top 10 profitable routes
Ryanair don't make that information public, also things can change massively over weeks in the business. Having seen some of the "low cost" prices on some routes, I'd be surprised if MAN-DUB was in the top ten. Having said that I doubt they'd drop it. Best analogy is Gatwick, and they're expanding there even though they are having to pay to fly from the airport and it's pretty congested much of the time.
Clearly Ryanair still want a piece of that pie.