I suppose we should be thankful that it actually made it into service, unlike the Nimrod MRA4!
I not aware of any reasons why it is going to be binned, not even on financial grounds. Never the less, it is another capability loss as I'm not convinced that a MALE RPAS (Scavenger) can replace this.
If you look at MALE RPAS radar (SAR & GMTI) published capabilities such as Selex Gallileo PicoStar's 20 km max range, it is a LONG way short of Sentinel's.
Maybe a HALE RPAS replacement such as Global Hawk, would have been a more understandable plan. Are we going to sign up for Eurohawk instead?
That's assuming there was/is a plan!!!