Seeing how there's likelyhood of US involvement in any action againt Taiwan China might take, and also keeping in mind the operations of american carrier wings, wouldn't it be of utmost importance for China to have/get some long range AAMs like R37? I would think that since Russians changed their minds bout their Tu22m export policy, selling something like R37 to China would be in the realm of possibility. Can that missile system be used on other aircraft other than mig31? Even if not, and especially in the light of today's BVR air combat, i'd say it's more worth to have a squadron of R37 equipped mig31 than two squadrons of Su27SK. Migs also carry R77 so as an interceptor it'd just fine. Even with that missile, it'd get additional range launched from speed/altitude that mig31 offers.