A really daft and only half-thought through idea, so do not bite. :-) I wonder if a modem could be designed which could listen to an extra input signal taken from a ‘quiet’ copper pair that is in the same bundle/main cable as your existing ‘signal’ DSL copper pair, that is, from the same bundle that is running to a group of properties.
The idea is that the modem could pick up a reference copy of all interference noise and some crosstalk. I am wondering if something very clever could be done regarding noise cancellation then? G.Vector is done properly, I would say, and this isn't. Is it meaningful / theoretically possible?
Regarding crosstalk, the quiet pair would have different neighbour pairs from those heard by your ‘signal’ pair so that could be a problem.