On or around 1st August the Harriers in store at RAF Cottesmore will have their engines run up to keep them in a serviceable condition. These anti-det runs allow the Harriers to be stored at RAF Cottesmore for an almost unlimited amount of time but don’t think this means the Harrier will be returning to service.
The amount of time that has now passed would make it extremely hard to reverse. The pilots and ground crews have now been posted to new roles or have left the armed services, BAE Systems have closed their Harrier operations and the staff have also moved on. Before you could start up Harrier operations again you would need to get all these people back and setup up the support contracts with both BAE and Rolls Royce. After then you would need to build up pilot currency and skills again which I would guess would take a year and even longer before there would be enough combat capable pilots to undertake operations.
A sad but more likely outcome is the Harrier will undergo the same fate as the Tornado F3 where the airframes are stripped down to parts which would be sold onto other air forces who operate the Harrier. What would be left after spares recovery would have any metals removed from it to be recycled and then the rest scrapped.