Hosts can turn their listings off at any time so they are hidden from the search results, but this is only to prevent new bookings. Once a host accepts a reservation, the reservation stays active, even if the host turns the listing off in the meantime. Marking a listing as hidden will not impact any confirmed reservations. Hosts need to honor all upcoming reservations you have booked.
While the listing is hidden, the public view of the listing will not be accessible. However, your itinerary will contain your host's contact information, as well as other useful information, like check-in information, the house manual and house rules, detailed directions to the listing, and the cancellation policy. You and your host can still continue to message through the site.
As long as your reservation still shows as "Accepted" in your Airbnb account, then your reservation is active. Your host should be ready to host you on the date of check-in. To see your upcoming accepted reservations, go to Your Trips.
You need to communicate with your host before the reservation begins so you can coordinate and ask each other any other lingering questions you may have. Guests and hosts work out details for checking in, exchanging keys, and checking out directly with each other.