Actually, I think Telecom Austria beat both of them to the first proper subscriber.
Swisscom are in good shape for G.Fast: they already had a "Fibre To The Street, FTTS" model, where they were getting fibre within 200m of properties, but using VDSL2 DSLAMs. A model that lies somewhere inbetween BT's "Cab" model for VDSL2, and a pure FTTdp model.
Swisscom's intention, with Alcatel hardware, was for their current VDSL2 DSLAMs to be plug-compatible with a future G.Fast model. A drop-in replacement, hardware-wise. Not sure what will happen to existing subscriber packages though.
this is also evident by the fact BT had to get the spec changed so it suited their business model of deploying from VDSL cabinets.
G.Fast itself didn't need much of a change to suit BT's longer ranges - just a higher aggregate power allowance, and bit-loadings of 13 or 14 (*). There were bigger changes needed in the business plans for DPUs - the nodes running G.Fast. Longer ranges imply more subscribers, more ports, higher vectoring demands ... and chipset designers needed to adjust their plans.
I suspect that BT don't intend for G.Fast to be *only* from the existing cabinets. In fact, the ANFP changes have been designed to cope with a multi-layered solution.
I suspect that BT really changed from a DP-centric focus to one very similar to Swisscom's FTTS: their own "inbetween" variant. It is obvious that phase 1 of an inbetween variant starts with the existing cabs anyway.
(*) - These changes went through as part of amendment 2 of G.Fast. It created a new profile 106b for this purpose.
It looks like amendment 3 went through last month, which properly introduced a 212MHz profile, something for G.Fast to run on coax, and added the ability to dynamically shift bandwidth between downstream and upstream. I'm not sure if the latter is coax-only, or works on twisted-pairs too; the ITU specs are still locked away.