From the email its states that:

If You are currently paying for vCloud Air OnDemand via a credit card. To ensure uninterrupted service and access to your instance, you can

• Transition your instance payment method to pre-purchased service credits via our Subscription Purchase Program (SPP)
• If you do prefer to keep paying by credit card, you may work with one of our VMware Partners who offer a credit card billing option

Effectively this is turning a Pay-As-You-Go service to one that is pre-paid and then billed in the rears via the Subscription Purchase Program. It also effectively blocks out the general public from swiping their credit card and spinning up VMs. These credits are available to buy through one of VMware’s Sales Specialists via an email address mechanism as pointed out in the FAQ here. The other option is using an vCAN SP’s ability to purchase credits and transact through them.

http://vcloud.vmware.com/using-vcloud-air/spp-migration

So what does this say about vCloud Air’s future? Honestly I don’t know what to make of this however I do know that it makes vCAN Service Providers who have online purchase facilities and automation (such as Zettagrid) instantly more attractive than VCA….hopefully it doesn’t work in the opposite and push potential customers straight to AWS or Azure. Interestingly enough VMware has addressed the question of VCA’s future directly in the FAQ.

Q: Is this action evidence that VMware is not committed to vCloud Air?
A: VMware remains committed to vCloud Air, and continues to invest in and operate vCloud Air as a business and platform with a robust roadmap validating our vision. We continue to offer our customers choices of how to extend their private workloads to the public cloud as well as how they pay for their vCloud Air instances.

Key Dates:

References:

http://vcloud.vmware.com/using-vcloud-air/vca-faq-cc-2016?mid=2402&eid=CVMW2000018547705

http://vcloud.vmware.com/using-vcloud-air/vca-faq-cc-2016?mid=2402&eid=CVMW2000018547705