Thanks! I don't keep up on SSR so I didn't know the walkway was under construction.
The MK buses will be running after midnight. You can take the resort monorail or boat back to the MK and then walk over to the buses. You can also cab back as your cab *should* take the same back roads to SSR. If you take a cab make sure to ask them if they can get you home by way of Vista Blvd past FW and Bonnet Creek part PO.
You may also want to have a "Plan B" about watching from the Polynesian Beach. There are reports that they restrict the beach to guests of the Polynesian only on NYE:
http://www.disboards.com/showthread.php?p=47415238 . Maybe the Top of the World lounge at the Contemporary? It might be open to non-BLT guests (but still DVC guests staying on points). Boardwalk has a party with a DJ and you can see the fireworks from outside. Also, I have heard that SSR has a really nice NYE party itself. You may just want to head home.