For a property mere inches away from the cabinet, it is plausible that the upstream rate could be as high as 40Mbps, even using the current frequency bandplan. If that were the case, then it would "only" be a matter of getting the cap changed; downstream would be huge too, and there would be no need to cap it to get the upstream that high.
However, for real distances away from the cabinet, it would take a change to the frequency bandplan. And, because of crosstalk interference between lines, it would be important that every line in the cabinet share the identical bandplan.
That is why, as the 17a profile was rolled out at the end of last year, and it included a change in bandplan, it happened on a cabinet-by-cabinet basis.
That 17a profile actually moved some of the upstream frequency band to downstream, so there was a general change that improved everyone's downstream at the expense of the upstream. The opposite of what you want though...
Finally, the 17a profile and the ADE17 bandplan is now the only authorised setup for BT cabinets, according to the Ofcom ANFP. So no chance of getting it changed
Having said all that, the cabinets can be configured with different bandplans - including customised, non-standard ones.
So, in theory - Yes. In practice - No.