I think this one needs time. Eastern have a reasonable network from SOU planned for this summer, which will probably open them up to a number of customers (NI, ROI, regional France, Gibraltar) who've never used them before and hopefully get the name out there a little more. They have a reasonable product with two modern ATR's operating most flights so may be able to make a bit of a name for themselves at the SOU end at least. I believe they had taken on a few ex Flybe CC so there may be an element of word of mouth there.
Hopefully it is still going ahead but they also announced a codeshare with Aurigny late last year, which would theoretically allow easy connections to Guernsey and Alderney from Belfast and others or vice versa if timings get aligned.