[sweeneyrod]

I don't think this is that jargony. Anyone in the target audience for the article should know what "churn" means, and given that knowledge should be able to work out what "net negative churn" means. Probably the clarification would've been better if it had started "meaning the revenue from usage-driven upgrades" (and likewise "usage-driven" and "net" in "net negative" don't add anything) but overall it should still be comprehensible.