So apparently, the world of Matt Reeves' The Batman has been designated as the Earth 2 of the DCEU's Multiverse. Whether this is just an internal designation or will be used in-universe is unknown.
https://www.cbr.com/robert-pattinson-batman-earth-2/
Anyway, the terminology is immaterial, at least as far as Batman is concerned - nothing about Pattison's Batman screams ''Golden Age Batman'' to me! But the fact that they are giving this reality a designation within the context of a multiverse does make me wonder if they plan on building a second shared universe where we could potentially see other characters. Either characters new to the DCEU (or the big screen in general) or reboots of existing characters. A rumor has been going around lately that JJ Abram's Superman project could be set on this Earth 2.
Should Pattison's Batman co-exist with other superheroes? Or should this be a Batman-exclusive world ala the Nolanverse? And if they throw in other heroes, should they maybe focus on more grounded street-level characters or bring in the full might of the DCU?
PS: According to some set photos and props spoilers:end of spoilers
other heroes, such as Superman, Wonder Woman, Flash etc. do exist on this world in some form, either as other superheroes or as fictional characters at least - given that there's some sort of party where the guests are dressed as these characters. There's an prop article however which seems to imply that Superman is real and operating in Metropolis. So who knows...