I suspect, though, that this story will only get bigger if it turns out that there are other Tory candidates who have non-dom status. Given the way candidate selection has been handled in recent years, there is no guarantee that CCHQ has established that all candidates are both resident in the UK for tax purposes and do not have non dom status. If CCHQ is sharp, it will set about establishing this now and, as Ben Brogan says, demand that anyone who wants to continue as a Tory candidate both be resident here for tax purposes and give up their non dom status.
How this plays locally will be well worth watching. Ben Brogan wonders if Goldsmith told his association of his status and if not whether they will kick up a fuss. I also imagine that this revelation will feature heavily in the Lib Dem effort to hold Richmond Park.