From the Kickstarter page FAQ:
Will Divinity: Original Sin 2 have full voiceover?
It's unlikely that DOS2 will be fully voiced. While we’d like to voice everything, this is a game with exponentially more dialogue options than Divinity: Original Sin (the recording of which took seven straight months!), and we don't think there's any way we can voice it all with the resources we expect to have. We've tripled the size of our writing team, so we're looking at at least three times more content to record.