i just had a crazy thought......what if kishi wants us to wait til we find the truth about madara(that may be linked to kakashi or obito in some way). then when that happens or the big event to kakashi happens kishi will release the gaiden. hope its true and if the gaiden is released this year that'd be awesome!
guys you know what, call me crazy but i think the gaiden might be shown this year(maybe kakashi's big event). cuz they're gunna have to show it sooner or later and remember in the fight with jiraiya and pein right before jiraiya died there was a flashback with narutos parents and the 4th was talking to jiraiya. which means sometime before that fight it could come out.