Possibly due to the delay in Star Wars we are seeing Sony shift around a few movies, including the new reboot of Spider-Man.
The live action reboot (second reboot) of Spider-Man has been moved up to July 7th, 2017. Originally it was penned for a July 28th, 2017 release. Pirates of the Caribbean: Dead Men Tell No Tales originally held the slot, but the film was moved up to a May release while a new Star Wars movie was pushed back to December.
Perhaps it is Sony and Disney working together since Spider-Man is now working alongside Marvel Studios films.
Meanwhile Jumanji has seen a hefty delay from it's December 2016 spot to a July 28th, 2017 release date. This film has even less details than the Spider-Man reboot as no cast has been announced yet, only director Jake Kasdan and several writers have been announced. The 1995 film of course featured Robin Williams as kids allowed a man trapped in a board game loose.
Personally there isn't much change. Jumanji was somewhat looking for a date anyways, and I wouldn't be surprised if it changes dates again. This is already the second delay for the film, plus Sony also has several other movies in the June and July slots including the Uncharted film slated for a June release.