I understand having disdain for Nick or Nick together with Adalind to the point that posters envision a different ending but I doubt the writers would do a complete 180 in the last 2 minutes of the show, moving away from a Nick/Grimm centred story to a Renard/HW centred story, especially with Kelly, the next generation moving away from the original premise, his father, whom he sounds to be very proud of. Nor do I see the same writers moving away (and completely off screen with zero indication within the show's runtime) from Adalind with Nick to Adalind with Renard while shoving Nick to some back corner somewhere, consigned to only working his murder cases away from dealing with wesen that threaten people or all of Portland and leaving all the heavy lifting to Sean Renard, a former BC lackey/power obsessed half royal. I am more than certain this is not what the writers wrote or wanted interpreted from that Diana/Kelly scene. The writers even went on to give interviews on the characters after the show ended to clear away any ambiguities. To disregard this is more about what viewers wanted to see rather than what actually happened.
If nothing is factual about Diana and Kelly meeting Nick and Adalind specifically and it's all conjecture, for all the statements pointing to Renard/HW using vague "evidence" from characters' actions, often from the earliest seasons, it is easily refuted by pointing towards more evidence of the same characters' actions in the last two seasons alone (and more if we're being generous) that say otherwise.
If nothing is factual about Diana and Kelly meeting Nick and Adalind specifically and it's all conjecture, for all the statements pointing to Renard/HW using vague "evidence" from characters' actions, often from the earliest seasons, it is easily refuted by pointing towards more evidence of the same characters' actions in the last two seasons alone (and more if we're being generous) that say otherwise.