There have been ebbs and flows over the past decades, and eventually they end up buying competitors.
You've been buying wine for a lot longer than I have, but it seems different now. The world is so much smaller, that they would have to buy not just all of the American competition, but anyone who makes kosher wine worldwide.
10-15 years ago they got exclusive US distribution rights to a new winery in Europe, and put them out of business by not bringing any to America. I don't think they could do that today.