On my install, the engineer adopted the first approach - transfer the extension wiring to a normal NTE5 faceplate and fit the interstitial VDSL filter. I believe this is the preferred approach.
In fact, the engineer installed a new NTE5 - the existing one wasn't that old and was undamaged, but was old enough to have a current style BT logo rather than the BT Openreach logo. I suppose he was going to have to open a new NTE5 for the faceplate, and as everything was unscrewed, it took him a few seconds to snip the incoming pair and connect it to the IDC terminals of the new NTE5.
The engineer took my old faceplate filter, despite it being privately bought. If I was quicker, I should have asked for it, as it was clearly a non-BT supplied one (it had IDC terminals for an unfiltered connection) and a friend could have done with it. I suspect it got thrown away along with its screws.
If you have an existing faceplate filter and wish to keep it, it may be worth removing it at the point you lose ADSL sync, especially if you have an IDC tool and are happy to reconnect your extensions yourself.