The 968 was doomed by two things: the early 1990s downturn in the economy and extremely high production costs. As much as a modernized generationally upgraded 968 would be cool, the Cayman is a wonderful successor to the well-balanced 968.
I am not certain that Porsche wants to compete in the sub-$40k market. As a small independent they could never hope to compete with the economies-of-scale enjoyed by Nissan, Mazda, or Audi (examples of large manufacturers who sell sports coupes from $30-40k). There is also the dimunition of value issue - Porsche is an exclusive and valuable brand that must be carefully protected (note how psycho they are about miss-use of their name, font, crest, etc.). If anything, Porsche wants to go in the opposite direction. Hence the Panamera coming out next year and possible follow-on coupe variants.
It would seem that the base Boxster will be the least expensive Porsche for a long time to come. And if you do a simple inflation calculator check on what a 968 went for in 1995 you will find that the Boxster is actually cheaper.
1995 968 base price: $39,950
adjusted for inflation: $49,705
2007 Boxster: $45,600