Personally I hope the game does not have a built in voice chat. I don't want to be expected to use it. Plus Discord is free.
There is just too much to lose with very little to gain.
If there is an expectation that you will use voice chat with random strangers you are bound to be subjected to some of the worst gaming has to offer.
Squeakers
Audio trolls who think its hilarious to see how fast they can force you to mute them
Children who have whiney parents telling them to get off the game
Sub humans who insist you know about their disfunction (drug habits, sexual kinks, mental instabilies, ECT.)
Crying babies
Dogs barking
These are all more common than not, and lead to terrible voice chat experiences. Personally my friends and I will use my Discord channel. If we want to talk with someone we will just invite them to join the channel. There is no need to tax the game client with a voice chat that will invariably not work for half the population and the other half will be comprised of a majority of people you just dont want to hear, ever.
I have no doubt that with as social as this game will be we will all find others we click with. And I do look forward to inviting people whom I do enjoy talkiong to, to join us on our discord.