Buster 15,
First off it's three squadrons and not two; 9, 12 and 31, secondly it may be a "perfectly capable first line strike Tornado GR4 fleet," but it's been in service for over 36 years and it has been worked very hard operationally for 26 of those years almost continuously.
Typhon and Lightning will have all of the capabilities of Tornado less the large Reconnaissance pod, and the GR4 doesn't go until 2019, when these capabilities will be worked up on Typhoon and on the way on Lightning.
Let the old beast go...