This doesn't help much, but I found three mentions of parry in the previews:
The first one, from the first preview, is seemingly contradictory. Combat is the same, but different (specifically simpler; less math), and it includes parrying.
The second one, from the second preview, lists "Reactions". Parry is one of them.
Regarding "Reactions", two main points: 1) when attacked a character usually gets the chance to react, and 2) a character has the same number of "Reactions" as "Combat Actions". Also, Reactions are not made during a character's Strike Rank, and there are four types: dodge, parry, dive for cover and free attacks.
The third one, from the fourth preview, merely states one cannot parry whilst in a Battle Fury.
I cannot remember if one could parry infinitely and always under the old rules, but it seems under these rules one may parry only a limited number of times per 5 second Combat Round and not at all under some circumstances.
The actually mechanics of Parrying are, however, still a mystery.
There is one more mention, under the weapons list, a Target Shield may parry ranged weapons.