Lets skip the fact that its been 20 years since Serenity, the possibility of Jayne being sidelined or written out entirely due to Baldwin being loudly conservative, and the likelihood of heavy handed allegory to current culture war bullshit being injected into every other episodes.
Marc Guggenheim's track record (the showrunner) is fucking terrible.
Arrow - the shining star of his resume due to it starting with 2-2.5 quality seasons before the subsequent 5.5-6 increasingly terrible seasons
Legends of Tomorrow - couple decent episodes sprinkled throughout 4 shitty seasons
Supergirl - fantastic pilot episode followed by 6 years of being a non-stop SJW dumpster fire
Carnival Row - excellent visuals and world building, nonstop heavy handed and shitty writing about inequality