Who knows with BT's trials
However, they are already aware of the fact that after application of G.INP, most lines run error free.... plus they know its already in use and working on ADSL2+ lines.
This isn't brand new technology, so if the trial is successful, I can't foresee any reason why rollout should be delayed.
Question is however will it be on only downstream on ECI and will Huawei be capable of this on both up and down?
Its simply setting a configuration parameter, both types of cabs are capable of doing it both upstream and downstream, so highly unlikely it will be cab specific.
I'm undecided how they will apply this. IMHO the easiest way for them would be to make it like 21CN DLM as a param. But it entirely depends on how much they want to keep the speed cap.
1) They could replace the speed cap with a variable target SNRm and reserve capping for lines seeing high error levels.
OR 2) They could adjust the existing cap levels to fit 3dB. Ive observed that rate limiting seems to more or less follow 6,9,12 dB, so that also would be fairly easy for them to do.
At one time BT were paranoid about users over-riding Target SNRm - they specifically saw (& cited) DMT-tool as bad in their eyes, because it easily allowed users to play with SNRm... which is why they currently use rate limiting rather than a variable target SNRm. So it depends if this is still a concern to them & if it is, then I suspect they will go with option 2.