It looks like there's no Highland Sleeper full service until the 12th. Although it says the line is closed until midnight on the 12th, meaning as it stands the Monday Sleeper to Fort William hasn't yet been ruled out, as it wouldn't be anywhere near by midnight.
Until then, it looks like trains to either Edinburgh, Dundee or Kingussie (depending on the day) and a replacement bus from there.
However, the latest I've seen is that some of the roads are flooded and replacement buses may struggle.
Anyone got a hovercraft?