I don't believe they will sue EVERY bot user, for just like Never Back Down said, it would cost them loads of money. I would really like to see if they actually go through with what they say.
Their legal team would end up losing money rather than making any money from this. The only people they would ever sue were botting websites and companie and perhaps large goldfarms. I don't see their lawsuits going anywhere at all, though.
I can guarentee you that they will be suing the larger companies, but the smaller companies and players are likely just a bluff, either way though I'm happy with the community without bots at the moment.