Much weeping and gnashing of teeth attends the premature retirement of the Harrier force. Those of us with longer memories, though, will recall that the original justification for the aircraft (in the ground attack role) was that its V/STOL capability allowed it to be deployed closer to the FEBA (Forward Edge of the Battle Area). The high sortie rate - attendant on the short transit time - thus compensated for the poor load-carrying capability and the limited range.
Latterly, the aircraft has been used to salve wounded pride in Afghanistan, where the vast preponderance of close air support has been provided by the Americans. Based at Kandahar, where facilities were fairly primitive, the Harrier was able to operate from the air base, in the space left by the Americans, when our heavier aircraft (such as the Tornado) could not, without considerable expenditure on infrastructure.
Nothing of this, however, makes up for the fact that the Harrier retains its limited load-carrying capability, and limited range. This, plus the fact that it is inordinately expensive to operate and highly manpower intensive, makes it a far from ideal aircraft.
On the other hand, the A-6 /Tucano B-2 option offers a better load/range/endurance combination than the Harrier. These aircraft are vastly cheaper to operate and, although not capable of vertical landing, they do have a significant short-field capability and can operate from unprepared strips. In many respects, therefore, this aircraft type could be a useful Harrier replacement.