I hope they don't do an in-game chat. My preference is to play the game when I'm playing it. Not chat about it. If I want to chat about Gwent, there are plenty of places to do so. So from a selfish standpoint I see no upside to the mechanic (though I recognize and respect that this is a preference that others disagree with).
Also, it definitely can be and will be abused. Yes you could create an option to not participate in the chat, but there's still going to be lots of incidents of harassment. People who harass others are going to push away people from playing. I want a large player pool. More players = more opponents = more fun.
Furthermore, I'd rather CDPR devs focus time and resources on making the game better than sorting through reports of abusive players. They would have to create some system to report abusive users. There is an opportunity cost associated with with having to monitor reports of abuse. They can't just have a computer automatically ban players who are reported for abuse - someone will have to look into the claims and see if it really is an issue. Do they create an algorithm that sees so many reports = instaban? Do they hire people to actually look into it? Do they have to keep records of all the chats on their servers to be able to verify complaints? Do they have to be some appeal system of bans? The bottom line is that means resources will have to be spent creating a system to monitor the chats and manually going through at least some of the reports of abuse. That's time and/or resources that are taken away from looking into bugs, improving balance, creating new cards, factions, SP campaigns, etc. I vote no.