They have offered this 'boost' since 2013, so I`d say it's safe to say it'll be offered again for 2017.
However, you can get those missing 5k miles much more economically than just paying for them.
Being UK-based, look out for cheap premium cabin weekend runs.
Example:IST, which BA sells for 380 pounds in business class (I fare) ex LHR - fly out on Saturday, fly home on Sunday, collect ~4,700 EQM. This route is even operated by a 767 with real CW seats, so the flight is reasonably nice.