I think the key issue is that you have made various assumptions of your own accord, and then you are getting angry because they haven't been realised - but they were never backed up by what the airport and the plan actually said.
As that article from 2015 states, the plan in the medium-term was always to demolish the main T1 building as the completed T2 would provide sufficient capacity. It was always likely that some of the T1 piers may remain for a period, although in exactly what configuaration is less clear. The renders shown in that article are early ones from the masterplanning stages, which invariably change once the scheme design actually starts to cost up the budget required to deliver it. Some of the later renders showed what appeared to be a physical link between T2 and T1 (and would then presumably carry on into T3). That can be achieved without maintaining the bulk of the main T1 building.
What would happen to the site of the T1 building once it was closed and demolished was never part of the Transformation Programme. At a minimum, that was a decade away from the commencement of the programme, and so it wouldn't make a great deal of sense to be including that in the programme (which was already a significant piece of work) when so much can change in that time. I'd imagine there are some masterplan documents in a room in Olympic House somewhere for development post-2025, but as far as I'm aware, that's not something that has ever been publicly released.
Many thanks for the clarification, these are more observations than any angry intent.
My curiosity is more about "the gap" between T2 and T3 and how the two will connect.
Had we kept T1 that would not be an issue but if its mothballed there still has to be a connecting corridor between the two. If it's to be demolished then likewise.
I assumed demolition would leave us a massive apron to make up for shortages where we are hemmed in on the perimeter.
I guess at the end of the day MAG don't need to divulge anything , but it's such a large gap it would be nice to know what the strategy will be.