Tense is used for more than just time.

Future time reference Before going into a discussion of the ways in which languages refer to the future, let us note that the future differs epistemologically??from the present and the past, as Aristotle noted. We cannot perceive the future directly or "remember" it??at least, this is what conventional wisdom tells us. (..) Normally, when we talk about the future, we are either talking about someone's plans, intentions or obligation, or we are making a prediction or extrapolation from the present state of the world. As a direct consequence, a sentence which refers to the future will almost always differ also modally from a sentence with non-future time reference. This is the reasonwhy the distinction between tense and mood becomes blurred when it comes to the future. (..) Semantics of (grammatical forms of) Future It seems fairly clear from the data (..) that the most typical uses of Future involve actions that are planned by the agent of the sentence. (..) Notice, on one hand, that "intention" more often than not is no necessary condition on the use of Future: in the majority of cases, Future can also be used for cases where the intentional element is lacking. If we have a sentence expressing intention but with no element of prediction, i.e. where the speaker takes no stand on whether the action will take place or not, it does not generally seem possible to use Future. We thus see that "Future time reference" is a more constant element of Future??relatively speaking!??than the modal features of this category, which in most cases may or may not be present. "Future time reference" could therefore be regarded as a dominant feature of (the grammatical forms of) Future. (..) The traditional view of the Future as a tense can be thus defended.

 I don't disagree with the analysis of the graphic present, etc. in this thread.

But may we not also say that the fortune-teller uses the present tense not because the future, from her point of view, is 'fixed'; but because she is reporting what she literally sees in her mind or crystal ball?

Cf. the use of the present progressive in the hypnotist's patter:

"You are getting very sleepy...you are falling asleep...you are sinking into a great white pillow...Now, when I click my fingers, you will open your eyes. {click} Now, you are very, very warm...so warm, in fact, that you must take off your clothes..."

MrP