We've seen and heard nothing from Neville since he asked for his release last October (which came after he was asked to lose to Enzo Amore for a second time after just losing the title to him). Unfortunately, WWE refused to release him from his contract and an update from Dave Meltzer points to the former Cruiserweight Champion being stuck with the company for quite some time.
Apparently, while Neville has definitely quit, he remains under contract and they still have no plans to grant him his release. As a result, he's unable to talk about the situation publicly without breaching his contract and there's no way for Neville to move to another company either. It's not clear how long he'll be stuck in limbo like this but it could be for the duration of whatever deal he signed with WWE.
It now seems like we won't see Neville wrestle at all in 2018 and his best option at this stage might just be to patch things up with WWE. It ultimately depends on how stubborn the British wrestler is...