So... people are terrified of a hypothetical?
Up until the point when they announce that singleplayer content relies on a multiplayer mode, I see absolutely no reason to be so pessimistic.
You're basically imagining a terrible scenario in your head and going "wow this sequence of events I'm making up sounds awful".
Why? Because that's the way it ends. Always.
For Example: i liked to play CoD-sp-campaign in the early days... but today they're just like michae-bay-movie. All the effort goes to mp.
And that's a shooter.
So what would mp in a RPG be? What would it offer? A great story, influenced by player choices? Let me laugh for a minute.
Then what else? Epic quests? Deep-RPG-mechanics? tactical group combat? You wish!
It will be either a wannabe MMO or some halfass modes like horde-mode or king of the hill.
In other words, the same thing dozens other games delivered before and better.
If there are so many mp-only-games, why can't there be room for single-pkayer-only games? Games which only concentrate on story, gameplay, characters... and in which the developers don't have to think "well, how do we implement this or that aspect according to sp and mp?"
If it's coop, then fine - that i can ignore. But no halfass mp, that even interferes with sp.