There is also the possibility that BA could codeshare on LGW-DUB. They are cutting back on some LGW routes in 2008 (NCE, PRG and possibly some others reduced) in order to free up capacity to retain some of the GB & BMED routes. That would fill the A320s and maybe even create scope for A321s if some of the options were converted and LHR didn't require them.
However, EI might want to have more aircraft and slots before agreeing that to ensure they can handle both their own and BA's traffic.