Personally - I say again, personally - I feel that the Achilles heel of any A330 'shrink' proposal would be the 60m wing. Just too darn big for many aerodromes...
But a modernised FBW version of the A310 Combi would be a totally different kettle of fish. A310+ with anywhere between 1 to 5 additional cargo tanks would be a most interesting proposal, I would suggest.