The term 'referee' will, as now, be concerned with deciding questions of fact and applying the Rules. He will be required to act on any breach of a Rule that he observes or is reported to him.
In strokeplay he will be expected to act in order to prevent any inadvertent breach of a rule but in matchplay he will let the players look after themselves (with a couple of specified exceptions).

The basic change is that he will not be required to actually accompany the players.

I cannot expand further as the change has not yet been confirmed.