The trail will be restored along the Purple line when that is done, IIUC.
And the W&OD trail is not going anywhere. This is not a serious project. The best way to provide transit service to Leesburg is improved bus service on the Greenway. The rail line is being pushed by Loudoun County rail fans, afaict, not even by pols from out there.
Im very pro rail, but there are higher priority rail projects (can we finally get funding for the new Rosslyn station, first step towards a tunnel to Georgetown? For a yellow line extension to Hybla Valley?).