Re: 40,000 sales staff
AWS has a lot of sales people, probably closing in on 1,000 around the world... a large salesforce and growing at any rate. Google is rapidly building a world class sales org too.
I don't think sales is any less relevant in the cloud world. They are just selling managed services instead of components parts. IBM, Accenture and the other legacy managed services companies have always had large sales staffs. If you are spinning up a few instances, you don't need a sales person and there is no ROI for the company to hire sales people to convince you use cloud A instead of cloud B. If you are talking thousands of instances and millions of dollars, no one is going to pop a credit card number in for that transaction.... You need custom NDAs, custom SLAs, intergation planning, volume based discounts... and the cloud company wants to make sure you see a convincing presentation to use cloud A instead of cloud B or C.
Having written that, EMC has always had a crazy large salesforce. Much larger than their competitors. Definitely a sales driven company.