More likely, it’s a Lestrange from an older generation, since Bellatrix and Rodolphus are stated in GoF to be contemporaries of Snape at Hogwarts (though not necessarily in the same year). The dates on the Black family tree would make Bellatrix too old to have gone to school with Snape, but only by one year; it’s likely that JKR screwed up the math, as she so often does, and meant for Bellatrix to be born in late 1952. Tom Riddle’s cohort would have gone to school in the 1940s, and could well have included the father or uncle of the Lestrange brothers.
So I guess this is official confirmation that it’ll only be one movie, rather than two. Goblet of Fire was too crammed as it was, and the books are only getting longer. Plus there’s the amount of material in the book which got postponed (or just outright ignored) in the movie. I can’t see any way a movie could remotely have room to do the book justice. Ah, well, we got three good movies, at least.