A Nonny Mouse, I would eat my hat (indeed, I would go out, buy a hat, BBQ it and eat it with tabasco sauce and mayo) if Ryanair were to do that.
The only way those 146s are going to figure in FR's future plans is if they're melted down to make beer cans, for sale on board.
O'Leary's not going to deal with a high cost airport like LCY, add to his costs by introducing any new acft type (and particularly not 146s) and divert attention away from what has been a very successful business plan.