Okay first off, I would like to preface this with letting everyone know that I don't look at spoilers- so theorizing on what happens going further could make me look really stupid. That said, I'm going for it anyway (along with yet again stating my thoughts on "Dark Dynasty."
Let's get the Metatron part out the way since it might be WAY off base. He went to get Cas's grace and the demon tablet, obviously he only made it out with the tablet. I've been wracking my brain trying to come up with reasons why Metatron would even be interested in the tablet (closing the gates certainly isn't on his to do list.) There is only, quite literally, one thing I can think of that Metatron would want the tablet for. Lets think for a second...
-Metatron wanted revenge at first, but in reality what he truly craved was power. He brought the angels back so he could be their new God
-The angels (with Castiel for the assist) realized what Metatron really was, so they locked him up. This guy wanted revenge before, think how he feels now...
-Metatron had his grace taken away, which is why he tried to use Castiels. (This actually puts a hole in my theory)
-Crowley has "gone soft."
-Crowley doesn't enjoy being King as much as he says, his heart isn't in it.
-True, his mother wants him dead via Sam which could cause trouble, but more than likely if things stay the course there will STILL be a "no touch" policy regarding the Winchesters. This kind of makes Hell a joke, yes?
Is this stuff random? Am I thinking too much? I ask because I see a regime change happening by seasons end. Metatron was an angel, now hes human so what does he have to do with the Hell stuff right? Here is my point...The tablet (as translated by Kevin) didn't have much in it besides the history of demons and closing the gates...The history of demons. As in, how exactly Lucifer turned the first human soul into a demon? How in turn that caused the demon to be the most powerful of all its kind?
I think Metatron is going to perform whatever spell necessary to make himself in Lillith's image so to speak. I know it seems like fanfiction but what else could he use the tablet for? And how many clues do we need to see that Crowley isn't the king he once was (and that there will be consequences for it.) I think Metatron turns demon (they could go crazy and him get grace somehow and go hybrid but that IS too much) and gains enough power to overthrow (BETTER NOT KILL) Crowley. That sets up our big bad for season 11, and yes Metatron was not a good villain in Season 9, but demon-Metatron could be a very different character. I'm not saying this is what will happen, i'm just throwing it out there and hoping someone comes up with a better reason for Metatron to have the tablet...
As far as Dark Dynasty, i've talked about it a lot and its been reviewed enough so I wont get into it too much. Poor script, characters made decisions that they normally wouldnt, etc...The Frankensteins have to be a red herring as i'm sure many people hope. Everybody we saw in their family gathering? Yeah well Dean is killing all of them hardcore. Charlie was like the sister he never had, whether right or wrong that she was killed off, it happened and it serves as a major catalyst for Dean giving in to the mark. The only death that would have hurt him more would have been Sam himself, and I think that has happened quite enough. I hate that they killed Charlie but I have hope it gives us a good finale. I saw a topic mentioning Cas might die. I said I don't read spoilers, but if there is any merit to that then I suppose Charlie dying makes even more sense, since that would mean TPTB want Dean to go super dark to where he may actually kill Cas as Cain predicted. He won't kill Sam. Maybe not for lack of trying (eventually,) but this MoC arc has gone on way too long, and I see it coming off thanks to Sam in the finale.
So, Dean leaves Sam in the dust, goes and kills the Steins so we don't see them in S11, probably goes back to DemonDean, possibly kills Cas, possibly goes after Sam in the finale, last minute spell to reverse the curse. No more mark. Set up for S11 would be the Metatron stuff worked in there...I have no clue where Rowena's character is going so I won't bother to guess. I'm really hoping the writers bring it home in these last two episodes, this show cannot survive another flat outing.