No major movie could ever draw in a large enough audience by appealing to just one demographic, so it's not an either-or question. The goal is to include a range of aspects that will appeal to multiple different audiences, that will draw them in for a variety of reasons. Of course it drew in a lot of younger Batman fans, and the reunion of Burton and Keaton probably drew in the Beetlejuice fans, but it also relied quite heavily on Jack Nicholson's and Kim Basinger's star power to draw in the people who weren't comic book fans. That's the whole reason for casting a big star like Nicholson or Marlon Brando in a movie like that, back when comics and sci-fi were a niche genre without the mainstream appeal and respectability they have today. (See also: George Lucas casting Sir Alec Guinness and Peter Cushing in his obscure little space fantasy movie starring three unknowns and a couple of robots.)
In this Flash movie it won't be, those films after 'Returns' never happened and Bobby Ewing will step out of the shower. But if you take the 4 films on their own then they are canon together. Kinda like the Terminator movies, you can choose which sequel to go next to the first two movies.
The Burton/Schumacher films are that weird kind of series, with both continuity and discontinuity between them. They're kinda/sorta one continuity if you squint hard enough but they differ enough that you can split two of them off if you want to.
Gordon and Pennyworth are the same actors. And there are a few dialogue nods to earlier movies, such as Dr. Meridian referring to 'skin-tight vinyl and a whip'. But Harvey Dent switches from Billy Dee to Tommy Lee. Gotham itself gets completely recast, looking strikingly different between the two halves. And when Keaton's parents are killed pearls fall to the ground, whereas Kilmer's parents die with roses falling to the ground. Sure, this is probably because someone remembered the first movie wrong (thinking of the roses that Keaton places where they died), but I still get to use it in the against column. For my money, Gordon and Pennyworth staying doesn't make the continuity a certainty any more than Judi Dench as M. Casino Royale is clearly not an in-universe sequel to Die Another Day. I say it's up to the viewer. ...but then they also have to decide if the Clooney Bat is a sequel to the Kilmer Bat or yet another do-over.
Aside from certain actors continuing in roles established in the Burton films, officially, WB never said the Schumacher films were a reboot or alternate world take on Batman. They're all in the same world.
The Schumacher movies may have been intended at the time to be part of the Burton continuity, but that doesn't preclude a new movie from disregarding them -- like how Superman Returns pretended nothing after Superman II happened (even though Returns wasn't meant to be a literal continuation of the Donnerverse, more of an homage) or like how the 1984 Return of Godzilla was a sequel to the 1954 original that ignored all its previous sequels. They're distinct enough in style that we can interpret them either way. Certainly the Arrowverse's "Earth-89" in Crisis on Infinite Earths appeared to posit a universe that continued directly from Burton with no Schumacher elements. It's natural enough that a movie bringing Michael Keaton back to the role would do the same. In Arrowverse terms, they can be considered doppelgangers -- like how Earth-90 (the 1990 The Flash series) has identical doppelgangers of Earth-1's Tina McGee, Tony Bellows, Julio Mendez, Trickster, and Prank, but non-identical versions of Barry, Henry, and Nora Allen, Iris West, and Sam Scudder (though E-90's Barry Allen is a doppelganger of Earth-1's Henry Allen). That's Wally, not Barry. (Oops, gave it away.)
That's the joke. Wally "I don't like time travel" West is now zipping through time Sam Becketting other speedsters.
Aquaman 2 is going to be called Aquaman and the Lost Kingdom https://gizmodo.com/aquaman-2s-full...Marketing&utm_campaign=dlvrit&utm_content=io9