EI-BUD,
When Ryanair took over Buzz there were loads of different reasons for closing down the airline - as they did also from Stansted for a month. The main reason though was because Ryanair didn't fly to Buzz's proposed destinations: AMS, CDG, BFS etc. And the base hadn't yet opened.
When Buzz announced BOH-PIK, FR immediately took over that route.
They have publicly announced (on local radio and in the press) they will be opening a base within 4 years or so. Ryanair usually want to place 3 aircraft at a base for economies of scale.
I agree with you about INV not being sustainable. I think the same about SNN. It is definately interesting to watch though.
Jet