Agree with the comments regarding Jersey. The thought of connection options on my previous post was somewhat Southampton centric - i.e SOU-MAN-ABZ which would probably have a small market with no direct ABZ service available any more (Eastern and Loganair via Teesside/Newcastle were direct, if not non stop). That would give it a bit of a boost alongside having to fight for the local SOU-MAN market and compete with Eastern.
I think there are enough passengers for one carrier to serve those routes. For two carriers each with a fairly niche presence though I am less sure, likewise of Blue Islands having or making sufficient aircraft available.