I do provide online mix/master services and have dozens happy clients around the world.
Need to speek in person? Skype, Hangout, Whatsapp... - I heard these apps been invented a while ago))
The pros of working with online services is that client can choose the studio/engineer which is most comfortable for him to work with.
And no need to be limited by just local studios.
Right now I am mixing huge album for Australian Ikonic Artists label having Skype chat frequently and solving out lots things on the fly!