The North remembers. The Boltons under Ramsay's leadership are likely to accelerate their downfall, as more rash actions are likely to be made over reasonable ones. This is hinted at when Ramsay suggests storming Castle Black and Roose is strongly opposed to the idea due to its recklessness which is likely to turn the other houses in the North against them. This somewhat mirrors House Manderlay's supposed allegiance to the Boltons and Freys in the books.

I think the main element of bullshit with Roose dying is that surely he knew Ramsay was plotting to make a power grab if Walda Frey gave birth to a son. You can speculate that he was planning to deal with the situation if it arose however Ramsay got there first, but given how many times stupid shit has happened in the show, I shouldn't look into it with too much depth.

Overall though, I found this episode was far better than the last one. It's good to see the Aeron and Euron making an appearance (where's the eyepatch bro?). I assume Yara will take the place of Victarion after the Kingsmoot, or possibly Theon depending on where he meant when he said "Home".