Realistically speaking, Lucas is a businessman and loves to capitalize on any opportunity that he can find.
KOTOR 3 will eventually be made (hopefully by 2010).
In order to keep the interest alive, the LucasFilms and LucasArts will probably release comics and perhaps collector's editions items that will fuel the eventual arrival of KOTOR III.
"Any fool with a d*ck can make a child, but it takes a real man to raise one..."
- Boyz N The Hood