And it would have been an even better set if they had included more of the young WHA players (Rick Vaive, Mark Messier, Michel Goulet, Rod Langway, etc).
Bobby Orr played 6 games in 1978-79, so he could have had his last card in this set as well.
A set with "natural" Orr, Gretzky, and Howe cards? That would have been a dream!