http://members.fortunecity.com/tengukun/wcw/roster.html
That looks like it could very well be the last WCW roster, just looking at it.
Booker T - WCW United States Champion
Shane Helms - Working on RAW
Mike Awesome - Touring with NOAH as The Gladiator
Rey Misterio - Working on SD (not part of Invasion)
Kidman - Released this past July
Shawn Stasiak - Inactive (far as I know)
Lance Storm - Runs a wrestling school in Calgary
Elix Skipper - Working in TNA
Evan Karagias - Inactive (far as I know)
Shannon Moore - Working indy shows
Chavo Guerrero Jr. - Now "Kerwin White" on RAW
Hugh Morrus - Works as a trainer at WWE dev. territory Deep South
Chuck Palumbo - Working indy shows (I think)
Mark Jindrak - 90-day no-compete clause just expired
Sean O'Haire - Doing MMA shows
Mike Sanders - Working indy shows
Kaz Hayashi - Working in Japan
Yun "Jimmy/Akio" Yang - 90-day no-compete clause just expired
So, I count four guys who were around since the Invasion, plus Misterio, who was with the promotion until the bitter end (but didn't sign with WWE).