For sure alternate airlines can look to tap the LCY market. Once again whether there is enough business to support 2 airports on similar markets is questionable.
There might well be BACX work as the Jungle jets are involved in weekend charters throughout the summer and they could most certainly operate from SEN rather than EDI / GLA.
Eitherway it is not going to be easy (no pun intended) to get new business in for the next few years.