Teri,
I think you are starting from the right place -- give them a thorough explanation of the field and of the employment opportunities within that field. But if you have significant question as to how realistic the student is being concerning their choices, it may not be inappropriate to broach the subject, so long as it is posed in the right way. I would not want to have a conversation that begins, "you won't be able to do this..." But I might consider a conversation that begins, "In order to complete the program, you will have to do ____.… >>>