Okay, but then what will the excuses be when the series ends and, as were have long been told, Dean is neither bi nor in a sexual relationship with Cas? What excuses will people try to come up with then? There's nothing wrong with playing with the ideas for fanon, but at some point, you gotta stop turning a deaf ear to what the writers have long been saying about their intentions.
What are the things the writers have “long been saying” that you’re referring to? Because whenever people make statements like that all they pull out are statements made back in the very early seasons. What has Jeremy Carver, showrunner since season 8, said about this? Please show me the interviews you’re referencing when you make statements like this and I’d be happy to review them.
Now I’ll address your use of the word “excuses.” People who want canon bi-Dean because he’s an excellent candidate for bi male representation (which is sorely needed) are pointing out the qualities the character already possesses that are common in bi men of his generation. If it doesn’t become canon that means someone wasn’t willing to take the leap, most likely the network because they have to approve such things and CW has squashed proposals for queer characters in the past. If it doesn’t happen it would be a shame because all the potential is there.
Now let’s talk about what the writers have “long said.”
“When you start a show, the plans are not set in stone. They’re really mutable, cocktail napkin sketches… It evolved from just, “I have to hunt down and kill my brother,” to these two mirrored stories about two sets of brothers, the brothers in Heaven and the brothers on Earth, and how they compare and contrast. A lot of it was dumb luck, and a lot of it was noticing the opportunities that we had in front of us, at the time, and taking advantage.” -Eric Kripke 2010 (x)
This is how writing for Supernatural works and it’s the reason the show is going into it’s 12th season. The writers don’t “long say” anything about the plot or characters, they’ve recognized from the very beginning that nothing should be set in stone, that it’s better to remain flexible and see where the story takes them. However there is something that’s been “long said” about how the writers view fandom
“The writer team, the producer team, do pay attention to the blogs and to the posts.”-Jensen Ackles (x)
The writers/producers of Supernatural interact with fans more than any other show I know of. Fanon headcanons get written into the show with such frequency that it spawned a new term, Kripked: “Referring to show creator Eric Kripke in Supernatural Fandom, to be “Kripked” means to have events in fic or Fanon, validated by new canon, reflecting the frequency with which SPN canon confirms SPN fanon.” (x)
Maybe canon bi-Dean will happen maybe it wont, but the potential is there. Having it go canon would be very important for the bisexual community because he already embodies so many of the traits that are often seen in bi-men of his generation.