ASW, ASUW and OISR skills are fragile, if you don't keep doing it, you lose it.
If the UK decides it really does need an MPA after all, however distant in the future that may be (now the pariah that was Nimrod has been 'removed'), who will train the 'new guys'?
Will the Seedcorn cadre need replacing in 2015? You're assuming that the overseas tour will be 3 years, it would make more sense to leave them there until they are needed back in the UK.
Replacement MPA options have already been investigated and the reports are back with the MOD/Government.
Most people in the know realise that, as an island nation, we do need a multi role maritime aircraft capable of long range SAR/SASS. It would be a shame if the delay in replacing the MPA was necessary to spare the Government/MOD more embarrassment by having to admit that they got it wrong in the first place.
Before I get angry ripostes about using the terms 'pariah' and 'Nimrod' in the same sentence, I don't agree with that sentiment, it's just the way that it seems, after the MRA4 were put beyond use with JCBs with what may seem to be indecent haste.
Nor am I commenting on the capabilities of the MRA4, there are plenty of other threads already devoted to that matter.