The idea of there being some kind of reboot doesn't surprise me in the least, but I'd have thought that WW'84 is the LAST film they'd want to mess with.
I'm also not really sure about the mechanics of such a reboot. With Flashpoint, you would have present-day Barry traveling back to a time before the other DCEU movies and potentially changing stuff.
WW'84 however is a prequel, technically, and not a time-travel story. Whatever Diana does in 1984 is technically part of the established timeline...unless some kind of time-travel element is involved. Of course, we don't know exactly how Steve Trevor shows up in the 80's so maybe there is time travel.
I actually think a better candidate for a reboot movie is the Supergirl movie which is rumored to be set in the 70's and feature Brainiac as the antagonist. Simply have Kara's rocket go through some kind of space-time warp and land on earth in the 70's, thus rewriting the timeline from that point onwards.