NYC/Nemo- should we stay or go.

I'm booked to take my 9-year old to NYC Sat.-Sun on a long-promised trip. We have tickets purchased, train travel reserved, and a place booked for Sat. night. I imagine if the city gets the 6-12" snowfall that is possible there, the city would really slow down, but the shows and concerts wouldn't be cancelled, would they? In bad weather, are the subways likely to be affected? We're hardy folk, and could probably hoof it to where we need to be. But I'm just wondering what to expect, and wishing I'd bought travel insurance

Hope everyone in blizzard territory stays safe!