Looking at Easyjet routes from EMA on the latest stats, they are all performing as they did last year, and have been making money for them for years so i dont think loads are a problem.
I have used EZY many times from EMA and flights have always been busy. I personally don't see Easy pulling out of EMA they have good routes and a loyal pax base. HOWEVER, it was not so many moons ago that the idea of Easy operating from BHX would have been simply laughed off this forum due to BHXs well documented anti-LOCO stance. But what do we have - Easy starting up at BHX as management there have suddenly woken up to the fact that pax are voting with their feet and using other airports offering more choices of destination and better value fares. OK so its two ski winter flights - but I really can't see BHX saying goodbye to Easy that easily now that they have finally enticed them in.
So IMHO, I think Easy could realistically set up a base at BHX (if BHX can offer the right price which I think they would be foolish not to) but only to complement that at EMA as there is sure enough demand for flights from both airports. The big worry for EMA is becoming a one horse FR airport, FR are really trying to assert themselves as dominant carrier at EMA. A good financial deal from BHX would lure Easy down, lets face it BHX has a big catchment area and pro-rata not a good range of LOCO flights apart from the usual sun destinations - eg there are no flights to MAD, BUD, SXF, PSA, VCE, VLC amongst others, all of these would be relatively easy to set up as EZY already fly into all of them from other airports.