This sounds like a good Staff College essay for someone. Bottom line is that no insurgency has been truly defeated by kinetic activity, regardless of which component delivered it.
I find the term "airpower" too broad - what exactly is meant by airpower? Which bit? If you mean anything that flies, then that is not helpful, as there are a wide range of capabilities under that banner. Strategic air is very different to the battlefield helicopter; and it was not airpower 'doing' ISTAR down the Falls Road - it was Army Aviation with heli teli. In my experience, there are elements in the light blue who tend to lump anything that flies under the 'airpower' banner, which is not doctrinally correct. AP3000 is all about the strategic level - AT, AAR, CAS, AI, OCA, DCA - and any time SH are mentioned it is (a) very brief and (b) in support of the land component.
I don't think we can answer the original question without defining which bit we mean. GR7 and BH in AFG are certainly doing their bit, what more could they do? They will not however win the campaign on their own; that is why we have to have boots on the ground as part of a wider, civil-led campaign. Thompson's principles from Malaya are still valid, and the contribution of the air component to success in Malaya is well made by Cumbrian Fell.