Privet Hedge - Neighbour severing roots
I wonder if anyone can help? We have a small, narrow and intertwinnend shared privet hedge with our neighbour. About 30 years old. Our side has a drive and 7 privet plants and they have 7 privets on their side (all cojoined to form one joint hedge). They have told us they they are going to take their hedges up and build a brick wall. To do this they have to severe our roots.(Our root system is mainly their side since we had our drive built). Would ours survive considering they would be hemmed in by a wall/driveway and the roots would have been severed? Or should we just replant and not take a chance (if the privets died it would be near impossible to dig them out once the wall has been built)?
Thank you for your help, its much appreciated!