I must admit, I'm very disappointed that Johns is essentially using an extension of his "seven colors" Green Lantern idea here. Wasn't the Speed Force generally implied to have something to do with the Fourth World's Source?
It's been described as a Valhalla for speedsters so often, turning into some sort of insanely wide-ranging effect of Barry's accident seems like an astoundingly ham-handed way of making him the center of all Flash lore. That's not just a problem in story terms, it also rather bizarrely interacts with the real-world publishing history. Barry Allen's not the first or only speedster in-story or even in publication terms by any stretch, yet that's being jammed in by Rebirth.
As to Thawne/Zoom embodying an evil reverse Speed Force principle....yeah. I don't think we need a Flash Sinestro Corps with its own power source either. Zoom's always been convoluted enough -- a time-traveling Rogue from the future who duplicated the Flash's powers -- that various later efforts to further complicate him (the Thawne-Allen rivalry, this Reverse Speed Force thingie) have detracted fromt he original character more than added to it. (Waid's take worked largely because at that point Zoom was technically "dead;" he was creating successor villains, not trying to revamp the existing ones.)
It also screws up Final Crisis (which is *not* redundant in this case), given the way that story rather clearly made Barry's return the universe's counterpart to Libra's. We even got the Speed Force as a counterbalance to Anti-Life, for Pete's sake! That simply doesn't work with Rebirth's revisions.
Between this and the "Henry Allen dies in prison" thing -- which screws up Johns's own Top storyline from the Identity Crisis tie-ins -- this Reborth is turning into a real boondoggle. It's actually managed to dampen my interest in the upcoming Flash series, something I thought was impossible given how much I wanted Johns back on the speedsters up til now.
I kind of have to agree, although I'm perfectly OK with ignoring the Speed Force connections to the Fourth World and Final Crisis. The Henry Allen bit is especially annoying to me. I'm waiting for the swerve that it was time-travelling Thawne that killed Nora Allen and ruined Henry's life in order to mess with Barry, thereby changing the timeline (and accidentally resurrecting the Top!), but I'm still not sure that'll save this idea.