Given that the only way to fly OW into KUL is CX via HKG, MAS in OneWorld would certainly help. But, appart from opening up KUL and other Malaysian points, would there be a significant advantage to OW customers?

For me personally, it would be great as I am planning a trip to KUL soon (obviously won't help for this trip - it will take many months before things get sorted). But prior to this I have never had a trip where a MH option would have been considered.

I guess it will be a matter of wait and see. Look how long it is taking for Swiss to be welcomed into the fold.