Unfortunately, as Nimrod didn't go into squadron service, there is no way to ever know how much more cash it would have cost to reach that point.
Personally I believe SFO when he suggests that the aircraft was pretty well ready - so the forecast that it'd cost 200 mill a year to operate etc seems fair to me. (Although it strikes me as odd - I don't recall seeing 'this will cost £X a year' being banded about for other aircraft - it makes me wonder if there's a deliberate policy to look on the black side...how much per year will Typhoon cost, for example...is that a common figure banded about in the papers?)
However, to a critic, the fact it didn't reach the sqns opens up the possibility that there's £X worth of further development and fixing needed before we get to that £200M a year point - and no hard and fast estimate of what that extra cost might be, over what timescale.
This allows lines to be drawn up - on one side, the SFO party (<g>) saying it's pretty well ready to go, in which case operating costs - in my view - don't come into the equation, I mean the kite needs fuel, servicing, crews etc but so does every aircraft in the inventory, on the other side is a group who can point to the idea that before we get to sqadron use the aircraft may be a bottomless pit we simply pour money into as it goes even longer past its supposed ISD.
Perhaps it would have been nice, in retrospect, if BWoS had said 'we guarantee we'll have these a/c on the front line for a total cost of £X' at some point. That way the critics couldn't make the 'bottomless pit' argument, which is - I think - the point that actually scuppered the program.
That the RN is now looking to reinvent the wheel is the stuff that 'the 2 Johns*' were so good at.
I think this argument is just going to keep cycling, as neither side will ever be able to prove their point. However, I enjoy a good argument, it keeps the grey matter turning over...
Dave
*(Bremner, Bird and Fortune)