Go out of business, yeah OK.
The only people that go over to Quebec are those that live near Quebec. Not many people from Fredericton, Moncton and SJ going to Quebec to buy beer, unless they are already in the Northern part of the province.
That isn't going to change, no matter the outcome of the case.
I was across last Thursday (as I was already in the area), during the day, and I think I might have counted 2, maybe 3 cars with Quebec plates on them, combined at all the stores, however there were 10X that from NB there, in the middle of the week, middle of the day.
What this case would do however, if the outcome is the demolition of the trade barriers, is you will see places pop up like you see in the US, which will be a mail order beer company, where you can order beer online and have it shipped to you. Obviously not cost effective to do on a regular bases, considering the shipping costs in this country, but for those beer you just have to try, but is only available online or in BC or something. As well, the infamous "beer of the month" club.