to be consider a premium carrier?

On a recent thread Swiss F was compared to TG F and the OP stated that Swiss was a premium product whereas Thai's wasn't. So it got my thinking what would Thai have to do in its premium classes in order to be considered a Premium carrier both soft and hard products.

I have only flown long haul on a handful of occasions in economy so I'm not in a position to add anything to this but would like to know what those of you who are frequent flyers think?

Thanks in advance