Actually it looks like during the re-org. taking place for 2005-08 the Black Watch will survive as an element of the new Highland Regiment (large regiment - think overstrength brigade) with the Black Watch being the 1st Bat. of this new large regiment.
Here's a link to the proposed order of battle for 05-08 as layed out by Hoon in July '04:
http://regiments.org/regiments/uk/lists/ba2005.htm