I had been pointing out for years that it was MRA4, not MR4, and the "A" could provide massive opportunities for the RAF. Compare the potential weapons load and loiter time for 4 GR4s and a tanker vs one MRA4.....
I originally saw one major problem, but as I see it now there are two. First of all, with only 9 airframes compared to the original planned 21, there will probably never be enough MRA4s to provide any for a dedicated attack role. That is the new problem....
Secondly, without deliberately being disrespectful to the maritime world, overcoming the Nimrod mafia's maritime mindset. Having said that, this might well not be an issue. The MR2 community seemed to adapt readily enough to the overland role in the latter years of the fleet - mind you, I bet the MRA4 opens its bomb doors at the same distance as the MR2, which I was told (urban myth?) was a throw back to the Sunderland, and the amount of time (and therefore distance) required to wind the depth charges out from the fuselage to underneath the wings.....
I guess, as has already been pointed out, overcoming the FJ mafia vested interests would also have been a major issue!