Lowbrow is a movement - slowly gaining momentum - that doesn't necessarily care if The Art World recognizes it as such. What matters to Lowbrow is that most of us average people do recognize it. Anyone who has ever watched cartoons, read Mad magazine, enjoyed a John Waters film, consumed a product with a corporate logo or possessed a sense of humor shouldn't have a hard time getting comfy with Lowbrow.
Lowbrow-the-Movement has here been assigned a "circa" of 1994, as that is the year that Lowbrow artist extraordinaire Robert Williams founded Juxtapoz magazine. Juxtapoz showcases Lowbrow artists and is currently the second best-selling art magazine in the U.S. (This seems like a good time to mention, too, that Williams claims copyright on the word "Lowbrow." As both pioneer and current grandee of the movement, he is certainly entitled.)
The roots of Lowbrow, however, go back decades to Southern California hotrods ("Kustom Kars") and surf culture. Ed ("Big Daddy") Roth is frequently credited with getting Lowbrow, as a movement, underway by creating Rat Fink in the late 1950s. During the 60's, Lowbrow (not known as such, then) branched out into underground Comix (yes, that is how it is spelled, in this context) - particularly Zap and the work of R. Crumb, Victor Moscoso, S. Clay Wilson and the aforementioned Williams.
Over the years, Lowbrow has unapologetically picked up influences from classic cartoons, 60's TV sitcoms, psychedelic (and any other type of) rock music, pulp art, soft porn, comic books, sci-fi, "B" (or lower) horror movies, Japanese anime and black velvet Elvis, among many other "subcultural" offerings.
Well, The Art World seems to get to decide these things. Time will tell. It's worth noting, however, that The Art World didn't cotton to many movements when they first emerged. The Impressionists endured years of lampooning by art critics - many of whom probably went to their graves kicking themselves black and blue for not buying early Impressionist works.
Similar stories exist about Dada, Expressionism, Surrealism, Fauvism, the Indian River School, Realism, the Pre-Raphaelite Brotherhood...aw, gee whiz. It'd be easier to list the times The Art World got in on the ground floor of a movement, wouldn't it?
If the test of time for legitimacy (as an artistic movement) means that Lowbrow speaks/spoke, in visual terms, to the millions of us who share a common cultural, symbolic language - albeit a "lower" or "middle" class, media-driven language - then, yes, Lowbrow is here to stay. Anthropologists will probably study Lowbrow in the future, to attempt to figure out late 20th and early 21st U.S. societal influences.