Is there an established way to lobby arXiv to expand the paper subjects it covers? A couple of days ago, it was announced that SSRN—a popular working paper archive in the social sciences—was purchased by Elsevier. As Elsevier is one of the most reviled of publishers, many scholars are now looking elsewhere for places to store working papers, and arXiv is an obvious candidate, but arXiv focuses nearly exclusively on technology and the natural sciences.

Is there an established procedure to petition arXiv to expand its coverage to include other disciplines, or do we just have to hope they notice and make the change?
Only arXiv offers the guarantees against new takeovers.
All the cloud services around might suddenly change their open policies at best. 

arXiv   platform is well engineered and there is already a Quantitative Finance category, adding more in the economics side should not be a problem, if they are willing to. 

One possibility is to start a campaign on specialised webservices such as change.org. 

With a lot of people asking, they might easily take into consideration the proposals to widen their scope. 

The major problem would be how to advertise this  campaign. Your question got an average 80 views in 10 days.