Yet again Bagso, you're mistaken. All the major operators at LHR are keen to grab as many interlining passengers as possible, it's not just BA who use LHR as a connection opportunity. This is why all the STAR airlines (come on Air India!!) are under one roof and most of Skyteam as well. It's not just a hub for one airline, it's a major spoke and connecting on point for loads more.
It is now contrary to IAG's commercial interests for LHR to be opened up again as they've just dragged BA short haul into profit and EZY would impact that profit centre massively.
However the consumer would likely win as BA would be forced to drop point to point fares in Europe at the same time as opening up new long haul. The down side is you bet everyone will be driving staff costs even further down to pay for it all.