I don't think Lando dying would have the desired effect. Yes, he was more major a character than most, but not enough in fans' minds to really evoke too much emotion. Han being killed and then Lando and Chewie hunting down his killers in episode 7 would have been much better.

Star Wars - Episode VII: Lando Gets Medieval

Seriously, though, this would've cemented Lando as a much more important character in the series. As it stands, I really feel no emotional attachment to Lando the way I do to Han, Luke, Leia, R2, 3PO, and Yoda. Lando was never given that much of a chance to truly develop his character.