I'll still be surprised if this is the end of this 'rumour'.
I have heard from four different sources that Jet2 is the airline in question (not all of them originating from SEN) including details of what the first destination will be - and it's none of those mentioned here in other people's posts. Other details obtained also suggested that things were at an advanced stage towards making an announcement.
I do agree that Jet2 would be a surprise but let's wait to see if anything is actually announced by the end of the year.