Why would the likes of Easyjet and Ryanair replace the lost capacity? More demand for their flights means they can charge more and make more profit. And where would they get the extra aircraft from that they'll need? As for Eastern and Loganair the former isn't in actually in great shape and where would the latter get the aircraft needed to expand even just to takeover the Scottish routes?
I do think that if Flybe go under so does the bulk of their route network. Which i why I hope someone will get on with it and stump up the cash required to keep them going.