For one thing, RIRs are not businesses. If they have less work to do they can have less staff. Worst case they could receive government funding like in the old days.
replyWould they in fact have less work to do? Government funding might be the right answer, but it's not necessarily going to happen automatically; the concern (which applies in other domains besides this one) is disrupting the means by which a public good is currently funded, without having a replacement already lined up.
replyAlso there's a subsection about tier 1 networks and those are businesses.