Well nothing has been said at Lossie on the Squadrons fate but as we start to see increases in Typhoons then my guess we will start to see the GR4s either depart or transfer to Marham. Still got another 18 months at least before the phoon gets to Lossie (thats not confirmed btw).
Realistically the wind down of Afghan and in 2 years the decision makers will have a better idea of the the big picture. (libya right now is the big question)