Why would you re-role the Sentinel. It will be (is) bought and paid for in the ISTAR role. It can't be much more expensive in it's current role than it becoming an Aeromed or Comms platform.
Not sure if it fulfils the Combat ISTAR 'flavour if the month' though?
Interesting to see that after USAF were thinking about binning their JSTARS in 2009- they've decided to re-engine, add SYERS III and increase the performance of the radar. Do they know something we don't? (apart from having more money to invest in the military)