Despite Julian's "SportBonus17" comment these buildings must surely be for two separate events!
I agree the US football decoration is most likely tied to the avatars in this thread and a Superbowl LII theme, however, the remaining buildings definitely have an Olympics theme albeit there is no Summer Olympics in 2018 only a Winter event in Feb.
I also note the statement in the last Announcement that Inno were done for 2017 and thus we're unlikely to see the Superbowl (and any potential Winter Olympics) event until Jan 2018.
OK, just seen the official Announcement and I'm wrong on all counts!!!