As noted by The Trek Collective, New Frontier will be returning in May 2015 with a new novel.
The entry on Peter David's page is listed near the bottom of the bibliography page under "Future Projects."Just ahead of that release, Peter David will be returning to Star Trek, with a new New Frontier novel in May. Peter David's website has that listed, with a link to an "untitled" listing on Amazon, which suggests the book will be released by Gallery Books, which means it will be in the larger trade-paperback format.