Having seen the video, it definitely addresses some vast improvements within the main Terminal building especially around check-in, security and the IDL, as well as baggage reclaim and immigration on arrival.
The decommissioning of the TTS, whilst it'll increase walking times, is definitely a bonus. Not to mention it's issues with maintenance and general aging (TTS breakdown isn't exactly an uncommon occurrence), it's also a huge capacity bottleneck in various ways. The question for me is what will happen to the below ground space within the Satellites? Will it lie dormant or could it be used for back of house eg. new handling agent offices/OCCs or storage?
One pitfall for me is landside arrivals which looks largely unchanged. That area is carnage even now so at 43mppa I dread to think. The only way I can see that improving is building a mezzanine level above for the retail areas or shifting them down towards the new space created at shoreline check-in. The previous arrivals terminal proposal before Covid better addressed this. Another issue as well is the forecourt in front of the Terminal which again looks largely unchanged. By then though it'll probably be £30 drop off so less people will use it anyway!
The vast area overlooked is the existing Satellites. They're barely big enough even now and have a lot of inefficiency in their gate set-up. The new Emirates lounge in Sat 1 between Gates 5/6 and 11/12 is a big space burden that will impact boarding capability for any future long-haul growth. That lounge should be located ideally either in the main Terminal extension or embedded somewhere along the new departure level link towards Sat 1 once STN-TP is delivered. There's then also a new orientation space needed once the TTS goes as the departing passenger point-of-entry into Sat 1 will move from the centre to the southern end of the Satellite between Gates 1 and 3 (which if anybody's been up there is not a big space at all).
Since domestic arrivals would turn into a bussing drop off near the existing CTA arrivals area, the current domestic area in Sat 2 (Gates 80-88) would be no longer needed as such, effectively bringing Sat 2 into a fully international facility. The plant room in what should be the main departure gates area above will inevitably need bringing into some level of use to maintain separation between departing and intl arriving passengers. Once the TTS goes the walkway from the Terminal into Sat 2 will need split level access through what's now the domestic area in order to reach Sat 2 Gates 20-39. Without that those Sat 2 stands would effectively become semi-remote stands with bussing needed in at least one direction of passenger flow.
Then there's Sat 3 and Sat 4 (or apparent lack of). This initial proposal at least seems to favour a bussing terminal over Sat 4 but I see two major issues with that. One is servicing short turnarounds on remote and the copious amount of bussing that will require all day long (not just for first wave like the current APV Gates 90-93 are used for) alongside all CTA and future domestic flights that need bussing. The second issue is aircraft upgauges with Ryanair Max10s and Jet2 321neos each with c230 pax being the future norm. Sat 3 will probably struggle with that and bussing those volumes of passengers will increase opex costs and impact OTP exponentially. For that reason alone I think Sat 4 will happen but maybe at a slightly later date.
The other thing I suppose is the naming of "Satellites" which I guess we'll have to start calling "Piers". Technically even now Sat 1 is the only true "Satellite".