Characters getting together and forwarding the plot isn't fanservice.
Some of you have become so accustomed to the "bad guys" winning everything that a couple of wins for the "good guys" is "fanservice".
Please...
I do think Cersei will try something though.
Well, the show started with villains who aren't really villains in the traditional sense because they didn't start the central conflict. And some of them aren't villains at all, or have a redemptive arc.
Then the real villains started shitting on the over-abundance of heroes and scattered them throughout the terrible world that's presented.
So the last act has been mostly comeuppance and there aren't enough villains except for whitewalkers who aren't terribly charismatic.
So if people call something fan service it's only because what's happening seems less like something that would happen, and more like something people would want to happen.
Example:
Roose Bolton seizing the opportunity to betray the Starks once he saw the war was going south seems like something that would happen.
Arya murdering the entire Frey family seems like something you would want to happen.