fundamentally they haven't changed,
GLD before change tank, after tank
MRD before change DD+tank, after DD+tank
LNC before change DD, after DD
PUG before change DD+possible evade tank, after DD possible evade tank
THM before change magic DD+back up healer, after change magic DD+ back up healer
CON before change healer, after change healer
ARC before change nerfed DD, after changer DD(maybe better time will tell maybe not)+ buffer
ok i grant you ARC has changed some what. but it was broken and couldn't stay the way it was, its still DD so they added to it not took away or changed it completely, but in general classes are fundamentally the same.