Monsters coaster has been a project that has been on/off for quite a bit, yes. But an entire redo of the park on a level near DCA is a fairly recent initiative that is gaining steam.
Avatar was a reach by Iger/Staggs to garner a bombshell property. But the announcement more or less went over like a lead balloon, and internally there doesn't seem to be a whole lot of excitement to get to work on it.
While on the other coast, Cars Land opens to fanfare and huge profit margins. That's the reason you're gonna see DHS done before Avatar, if you ever see Avatar at all.