The problem is, indeed, we don't know if there will be more stand-alones or not. The news/rumors can be interpreted different ways regarding the franchise's future.
Snyder's comment did not help.
Many fans are worried about the franchise - just go to the premier Superman site (SH) and read the comments.
The impression is out there with some that MOS was a disappointment to WB financially and that Batman is being brought in to salvage the next film.
Impressions take on a life of their own. I just read this at a movie site.
"Production on the Batman-assisted sequel to Man Of Steel is expected to begin next year and Warner Bros are targeting a summer 2015 release date"
http://www.nme.com/filmandtv/news/br...f-steel/316548
WB needs to get on top of this from a publicity standpoint - nip it in the bud.
How?
Have Snyder announce that, after WF and JL, another stand alone Superman film is planned.
Even if that is not the case, remember they announced an SR sequel which was probably never in the works anyway, it gets WB on top of the PR situation re: MOS.