If WS-Federation/WS-Trust are deployed as part of a service to expose consumable ADFS endpoints, is there a dependency on Kerberos?
For example, if Web Application Proxy (WAP) servers were being implemented as part of an ADFS roll-out and the WAP severs were not joined to the domain, will this limit the ability to consume WS-Federation/WS-Trust endpoints exposed by ADFS?
No, WS-Federation/WS-Trust is independent of Kerberos. Kerberos is just one option out of a range of authentication mechanisms that can be used in combination with WS-Federation/WS-Trust but it is not the only one, nor is it a requirement. Also, proxy servers may be deployed independently of the authentication mechanisms for WS-Federation/WS-Trust unless you want to apply restrictions on those mechanisms.