Well it seems that this Virgin Atlantic deal is more interesting than I thought.
Ryanair is trying a hostile takeover of Aer Lingus. If that goes through, Ryanair has signed an MOU to give the Heathrow slots to BA. Those slots are the ones Virgin was counting on for the domestic feed from Manchester, Edinburgh, and Aberdeen. It turns out VA was going to wet lease 4 320s from Aer Lingus who would crew and fly those jets. But that won't be possible if BA's gets control of those slots. Seems VA doesn't have any scope provisions either if Aer Lingus was going to do the flying. At least that was my interpretation from the Aviation Week article.
IAG, Ryanair In Potentional Deal For Aer Lingus Slots At Heathrow