Although Fantastic Four has been launched with a new #1 many times in the past, looks like this time it might be for a bit longer due to disputes between Marvel and Fox (and possibly low sales as well).
Although Marvel still has continuity going back to the 40s (Namor, Captain America etc.) Lee and Kirby's Fantastic Four which first appeared in 1961 is often credited with the launch of the Marvel Universe brand as it is today. The comic has experienced a few up and downs in it's time since Stan and Jack left, and hasn't exactly been a huge seller since then as it's been eclipsed by Spider-Man, X-men and more recently the Avengers in sales and popularity. So we'll see how this turns out.