You may not be surprised to hear that I've given a bit of thought to the question over the years.
The platform for a BA Greek major should probably have about 20 "US-semester units" in the first two years. (These are typically the units that are 'assumed' and 'pre-requisite' for the actual work of a literature major in the language). They would be taught communicatively and cover all usable* grammar. The remaining part of the major would have an additional 30 "US-semester units", most of which would be taught in Greek. Imagine students listening to a lecture on the development of the Hellenistic novel in Greek, or Plutarch's biographies, or Paul's development and thought. Some senior term papers would be written in Greek. Some classes could be taught in [English/local language] in order to mesh with breadth requirements of US universities and to allow participation by non-majors, e.g. archaeology of Greece/Israel, history of Ancient Greece//Israel//Middle East, or introduction to linguistics, discourse grammar, or an exegetical class perhaps only requiring a 10-15 unit 'reading knowledge' of Greek. Some schools like a literature survey class in translation, too, e.g. "Jewish non-canonical pseudepigrapha in translation".
Level of vocabulary to aim at? 10000 words is a good target, and I would expect students to control 4000-5000 words pretty well. 50 units in a communicative environment can go a long way.
Such a program outlined above would need about 4 professors to cover ongoing courses at varying levels. Basically, a good literature program at a good university has that, or more.
How far away are schools from this ideal? So far that they have not even imagined it.
How to get there? Have a patron write me off-list.
*"usable grammar" may or may not include introductions to dialectical and diachronic vageries. I would probably end up reserving readings like Lucian "Syrian Goddess" and Herodotos to 'upper division', post-20-unit courses. Also classes on poetry, from Homer to the Greek Anthology to Nonnus on John, would be 'upper division'. How much of a preview should be put in the first 20 units is negotiable.
PS: the 'paired' language for a double major would not be Latin, wonderful as it is, but Hebrew, with all of the same goals and standards. Aramaic can be saved for grad school, or else an introductory survey can be included in a 3-6 unit course for those already beyond 30 units of Hebrew. (Reading Aramaic is about like teaching Dutch reading to a German, or Spanish to the French. Targums are a good place to start for reading-only and can be paired with an introduction to Hebrew midrash. Syriac is the best place for a full working language.)