Is the Pink Letter from Ramsey or is Jon being Catfished by the Umbers or Sansa? As for King's Landing...the last time an army was let through the gates = Robert's Rebellion. I have a feeling either the Lannister or Tyrell army will be destroyed. Most likely the Tyrell.
Not by the religious freaks though, right? I mean, they don't even have swords or armor. That's why I find that whole arc kind of stupid. When Cersei was imprisoned, I'm not sure why the King's Guard and the Lannister army garrisoned in King's Landing didn't just wipe the floor with them to release her and Margary.
I think Jamie and Cersi use the Tyrell army and then turn on them. Maybe it goes the other way around. The religious freaks could also be a huge power though. All we see are the main guards. If it happens like he says "powerless have the numbers'' we could see city wide revolt. It seems like the calm before the storm at King's Landing. It is going to be messy which has me intrigued.
I think the first scenario is most likely. Remember after Myrcella died and Jamie is consoling Cersei, he basically says 'Fuck everyone who isn't us and they will take back everything taken from them and more. That said, the Tyrells seems to have provisions that they've been ferreting in High Garden to keep the high born in King's Landing fed.
That's an ongoing book question as well. Did Ramsay actually send the letter or did someone else. Personally I don't think the show people would show the Bolton dude ride into castle black if it was an Umber double cross plot. I think it was Ramsay who sent it.
Cersei hates Margery and I would be willing to bet that the ultimate plan is to kill everyone in the faith militant and have the Tyrell's killed in the process like Cersei tried to do with Tyrion at Blackwater.
What played out was much better than the theory. I know, I know some probably hated the episode...but Wow. The best so far in my opinion.