You're looking at it from the wrong end of the market. Paranormal, zombies, etc. burned out over a year ago on the acquisitions end.
I don't think zombies are dead (ha!) yet, at least I hope not. There aren't that many YA zombie books that I know of - Forest of Hands and Teeth obv. and the upcoming Courtney Summers book, This is Not a Test. There were some other comedy ones (can't remember any names), what else is out there? There seems to always be a couple around but I don't remember a huge influx.
Are ghosts played out? Because I'm currently querying an MS that has a ghost (though there's no romance between the ghost or any human characters), but at the same time, it has unique aspects, like the setting, plot elements, etc.
I would love to see more ghost stories - I loved A Certain Slant of Light by Laura Whitcomb.