WWDC is historically very light in the hardware announcements - that coupled with the 2015 model was announced less than a year ago (October 2015) makes the chances very slim.
Looking at the buyers guide, makes it look even more slim - the iMac is the second newest refresh at 226 days.
Looking at the buyers guide, makes it look even more slim - the iMac is the second newest refresh at 226 days.