The people who are always in the discussion threads will stop posting because there's no point in posting if there's no signature campaign.
You're wrong. The ones solely posting for their signature earnings will stop posting, so far I agree. But on the other hand, most of them don't contribute much to a discussion anyway, do they?
On the other hand, there are many reasons for engaging in a discussion besides signature earnings.
There'd be some people who'd continue posting though for the sake of keeping their accounts alive and to make them seem that they don't mind not getting paid by posting.
There'd also be those people who either have never been part of a signature campaign or have not altered their way of posting by being in a signature campaign (both were still existent, last I've heard), which would not at all be influenced by this "signature-fee week" (besides their earnings dropping for the latter, which wouldn't change their posting style).
gotta understand signatures means business. It's what makes users stay.
Fun fact: It's also what makes users leave.
That being said,...
The idea is stupid -snip-