"broaden" = dumb down, right?
Have you noticed how many games published, directly or indirectly, by EA fail because they do "good, but not spectacular"?
They're adding co-op (online only, no locals allowed, you filthy peasants!), you're gonna be fighting humans, and...oh yes...cover-based shooting.
And they have the sheer audacity to just assume a sales figure of 5 million at the bare minimum.
When they realize that there aren't 5 million people willing to shovel out fistfuls of money to EA for a sub-par, 6-hour long campaign (plus multiplayer, because that's what REALLY matters, right?) They're going to blame pirates, used games, and steam sales instead of blaming themselves for turning a good, but not spectacular (see what I did there?) game into a mediocre-at-best shootyfest.
I wouldn't be surprised if they removed the limb-cutting mechanic entirely, and just made it into "shoot everything forever until it stops moving"
TL;DR: Dead Space 3: The death of a franchise