I expect that congregations that are not donating enough each month will be given the amount that is expected to be received from them and thus could be based on a publisher head count just as are the circuit assembly costs.
Yup, I've speculated on that exact scenario. It's simply too easy for them to roll this out as "nothing to see here...business as usual. Brothers, your congregation already commits to a pre-determined amount each month. At the Circuit level you already use a per-publisher calculation methodology; your congregation already uses a per-publisher donation calculation for CO insurance, disaster fund, etc., so nothing has really changed!"
BAM!: Tithing-lite