Still trying to figure out the focus on "no lounge"....
I don't like it, but I can see seat selection being broken out from the bundle of services being offered in an ET fare. You book the ticket, pay for the ticket, print/collect the boarding pass, check your bag (or not for an HBO fare), get on the plane and have something to eat or drink.
The cost of lounge access for an ET passenger is unrelated to that. at least from the passenger's perspective and hard to quantify from BA's. I could go in the lounge and sit there quietly, or I could pound down a dozen glasses or wine and eat every crumb of food in the room.
Now BA could go the US model and only give lounge access to LH F/J pax, paid members and the highest elites. Domestic F/J pax are not even given access. But until they start doing this, I think an attempt to debundle the lounge really would be the straw that broke the camel's back.