How many movies do we need to re-tell Superman's origins?
To be honest I've lost count, and I've never seen a good Superman movie (but maybe the character doesn't click with me? I'm a Deadpool and Power Girl kinda guy)... anyway, Supeeman Legacy is *going to flop, but not because what you're thinking, but because DC is trying to cash-in the experience Gunn developed with Marvel... and hopes for Gunn to carry out a huge weight of flops after flops of DC movies... Dark Knight is the only memorable DC movie I've seen in 25 years.
Maybe Batman Returns, but that was 1992 (saw it in 1997 after watching Space Jam) and we didn't had a "standard" yet.
DC is going to blame Gunn if flops.
DC is going to praise DC for having Gun if not.
"Hey... can you do us now a Batman X Lobo to compete against Deadpool and Wolverine 2?"
"Hey, can you make now a Wonder Woman? But cast that Korean girl from Gilmore Girls... make it work or you're fired!"