Many owners visit all year and that adds to the 35,000 always here.
Yes, but. . .
Spread those numbers over 103 linear miles from Hatteras to Corova Beach (and I think the 35,000 includes all of Currituck County (i.e. the mainland too) and the mainland portions of Dare County that aren't really on the banks (think Wanchese, Manns Harbor, etc).
In a normal year, that is, not this one, after the Home Tour in the second week of October, it's mostly just permanent residents and second home owners. Thanksgiving and Christmas-New Years draw some visitors and lots of non-resident property owners. There are other events that do the same like Taste of the Beach (February?). Then there's biker week. April is the big month for coming down to plan weddings. Also it's the month rental property owners come down to work on their homes. But let's be honest. None of these look anything like the summer season - to the delight of at least some of the permanent residents.
A lot of the restaurants do shut down, some for the whole winter season, some for a month, and some for only a week or two. Try to find an open restaurant in January on a Monday night., Or try to find a restaurant open after 8:00 PM. There are some of each, but not many.
This year the rental season will last at least through October, But some restaurants have already given up the ghost, and at a 50% occupancy limit, more may do the same.
If you like to be alone and get out to enjoy quiet nature, you'll be fine. If your plans depend on eating out a lot and spending quality time sitting on the beach, you'll end up feeling like your average summer tourist on the fifth day of non-stop rain.