Erm..Yoda was pushin 700 when he dueled Dooku.
Yea but Yoda is not human.
I do feel if there is another Jedi Knight then there should be another hero. I like Kyle but I think the way in which they ended the story will put a damper on a sequel. For instance he is in love now. According to what we have seen in the movies Jedi's aren't really supposed to be into that.
Also Kyle got sucked into the force (JK1) not very willingly. He almost turned (MotS). And in the beginning of JK2 he wants to stay away from the Force and only turns to it again to get Desann. In the end he say he will think about continuing training when he gets back. He is kinda flaky on the whole Force thing and is not very dedicated IMHO. I want a true Jedi in the next one.
My suggestion is a twist on things. We saw how great Tie Fighter was because you played the bad guys (plus it was a great game) How about assuming the role of a Dark Jedi trying to accomplish something for his Master?