Take everything you currently hear with a grain of salt.
The first Batman movie (after '66) had been planned for since the Superman 1978 movie and went through many changes. It wasn't released until 1989.
Other Superman ideas had been kicked around since the early '90s. After a lot of changes to the various scripts, it was announced that Superman Lives would be directed by Tim Burton and star Nicholas Cage as Superman. Those things never came to pass (although they did get paid for doing almost no work).
The buzz about a Batman: Year One was all over the place... then dissapeared.
A release date was set for summer of 2004 for Batman vs. Superman by WB... but never went anywhere. Instead it became Batman Begins and Superman Returns.
A few years ago, Sony said that everyone would be returning for Spiderman 4... then it was rebooted with a new cast and crew.
The next X-Men movie that was supposed X-Men: Origins: Magneto. That was scrapped for "First Class."
Ghostbusters 3 has been talked about for decades and gone nowhere.
Abrams said Star Trek canon would be preserved
Basically, unless filming is more than a few days, any movie idea is just that- an idea. A blurb from one or two people means nothing... a lot of times, it doesn't mean anything coming from the studio.