With regards to EZY, I very much doubt this announcement is a 'another nail in the coffin'. If you compare other regional airports across the UK; FR, EZY and LS competition is far heavier than what will be STN.
EZY won't close their base at STN because if anything it used as a bargaining chip to get lower rates at Luton/Gatwick. The growth agreement signed by MAG and EZY back in 2013 was used for EZY to get a better offer at their home at Luton.
Load factors and yields from STN on EZY's routes seem to be extremely good on all their routes, even on EDI and GLA with stiff FR competition.
I'd put a bet on EZY expansion at STN in the near future. With LTN and LGW full and still many unserved or underserved routes from STN. EZY could tap into Paris CDG, Rome FCO, Venice VCE, Barcelona, Gibraltar, Zurich, Geneva, Tel Aviv etc (to name a few).
I think this announcement is a blow for Southend. I reckon at the end of the 10 year agreement with Stobart, EZY will pull out. So many failed routes... EDI, BFS, NQY, KRK, SXF to name a few and with BCN and VCE ending Q1 2017.