Got talking to a very friendly member of staff on Rita this morning. We got talking coasters and SW8 came up. After a bit of pushing, he told me all he knew. He said that, whilst no official announcement has been made to the staff yet, they all know what it's going to be. He said it's supposed to be a wooden coaster, most likely for 2017, but would say no more.
It's a fairly unreliable source (he seemed quite confident in what he was saying, but was definitely a new staff member) so I wouldn't trust it too heavily, but it's very interesting.
Burniel | Great at theme park knowledge, not so great at designing signatures.