Thanks all for your responses. I'm relieved to say that it all worked out and that my head started to spin when I felt I had no options and the clock kept ticking forward.
For what it's worth, the guests were not flying in, as I do usually ask for that information. I did call the number in Russia, to no avail.
Lessons learned:
1. For peace of mind, don't accept guests with no reviews
2. Expand on, and clarify, House Rules when it comes to guests communicating with any delays in check-in time
The only really bad thing that happened, unfortuantely, was an extremely rude Airbnb Customer Service person whom I reached at the SF office. She actually hung up on me as I tried to acertain if Abnb has a guiding policy on extremely late arrivals. All she kept offering was that I could cancel the reservation. Not ony was that an option contrary to my best interest, but, also not in teh guests beset interest either -- I just wanted guidance. A second call to Abnb was much more pleasant and reassuring. That person actually offered to call the foriegn number as well to see if they could get any updated information from the late guests.
Anyway, hope this helps someone down the line.