During their ongoing presentation to their investors, Disney's CEO Bob Iger has just promised that the events of Captain America: The Winter Soldier will feed into Avengers: Age of Ultron and "some facets" of Agents of SHIELD. Which facets? That's not really the point. I think he was letting us know that the crossover will be partial, and to not expect Agents of SHIELD to suddenly turn into Captain America 2.5.
It's become more and more obvious that the Avengers film will have to build on the events of Iron Man 3 and The Winter Soldier, perhaps less so the more self-contained The Dark World.
At the same time, it's also obvious that the audience wants Agents of SHIELD to tie in with the movies more closely. It was recently promised that Sif will appear in the show, and that got a lot of folk excited. Iger was trying to engender the same kind of enthusiasm with his comments today, I'm sure.
Personally, I don't know that SHIELD really does need to tie in with the movies. That's just a superficial fix, I think. It needs to work on its own terms, at least in the mid and long terms.
I think the dwindling audience for SHIELD was precipitated by a misunderstanding in the larger audience: they wanted superheroes, whether or not they were original ones or not, and not a bunch of agency suits.
But had the show opened up with a series of consistently strong, rich, smart and well-structured episodes – and it did not – a graph of the show's viewing figures would have looked a lot less tragic.