[Not Official] The press conference is tomorrow Thursday at 10am, but it has already been revealed by a reliable source that Kevin Magnussen will continue as a McLaren-Honda driver in 2015.
The Daily Mail and The Telegraph report that Jenson Button will be staying, in which case the Dane’s status will be reduced to reserve driver.
UPDATE! BBC also reports that Jenson Button will partner with Fernando Alonso for 2015.
GRANDPRIX20.COM 
BBC are saying button has the drive
nice