It is also possible that the speaker is more concerned with the pure certainty of the action happening than with volitional aspect that might be implied by the use of WILL by itself:
Emma will be seeing Luke tomorrow.
Some writers claim, with some justification, that this use of modal will + a progressive implies, by its lack of reference to intention, volition or arrangement, a 'casual' future. Depending on the context and co-text, the speaker may be intending a ‘casual’ futurity, or may be indicating a situation in progress at a particular time