Is ATM being replaced with other WAN technology? What is this technology? What Cisco certification will help train for this?
ATM is not being replaced as such, its just geting obsolete due to various other technologies which provide greater flexibility, more value added services and a better ROI.
Some of the happening WAN technologies currently because of the above reasons are MPLS and Carrier class Metro-E.
You can get in touch with a Cisco learning partner to attend a 1) Metro-E Bootcamp
and 2) MPLS and Advanced MPLS Bootcamp.