krispin41 mentioned the parade. The nighttime parade is definite -- the Disney Auditions site was recently looking for performers for a nighttime parade. So that one is happening, for sure -- but what is rumored about it is the parade's name and the concept/theme (probably a variation of "Paint the Night").
One of the rumored -- and very likely -- events will be a new fireworks show. I think it is 99.9% certain to happen.
There has also been a rumor of a new Castle show of some sort, but maybe it would tie in with the new fireworks? I'm not sure. The "diamond" theme for the 60th anniversary seems like too good of an opportunity to pass up when it comes to the Castle. Disney will have to do something diamond-y on the Castle.
There is also a strong likelihood that World of Color is getting some sort of new show (along the lines of what is happening now, with Winter Dreams, but non-holiday specific).
Apparently there are going to be assorted diamond-themed decorations sprinkled around
Disneyland.
As
OKW Lover mentioned, a new Soarin' Over the World (or whatever it is being called) movie is rumored to be creeping in sometime soon -- which would make sense, as the land that houses Soarin' -- Condor Flats -- is apparently getting a facelift of sorts, with some tweaking of the present aviation theme. If the land itself is going to get a bit of a makeover, I think that it stands to reason that the new Soarin' film might be coming soon, although I don't know if it would arrive in 2015.
The link that
figment_jii provided above is a good one --
HydroGuy will, I'm sure, keep that thread active and updated as news comes in.
As for the things that will not be happening until later in 2015 (if they happen at all):
There is a rumor that the old Christmas star (which used to sit atop the Matterhorn decades ago) will return for the 2015 holiday season.
There are rumors that Mickey's Halloween party will move back to DCA for 2015, presumably to not interfere with the new parade and new fireworks in Disneyland.
