Detail #147: Finnic Differential Object Marking taken to 11

I was discussing Finnic object case thingies with badconlangingideas' curator, when I made a mistaken claim and caught myself doing so and corrected myself. The claim came from too quickly reconstructing a memory about what Livonian does. Livonian does an odd thing - viz. it permits accusative with negated verbs, which is exceptional in the Baltic-Finnic languages. However, we were discussing a different thing altogether (viz. the anti-ergative alignment here). Let's imagine a Finnic language that extends the use of accusative along the lines that Livonian did - so that the more concrete the verb, the more definite the object, etc, the more likely the object is to be accusative. Let's further have the language reinterpret the accusative as the distinct accusative case. Suddenly we may have a three-way distinction for those verbs that lack a syntactical subject:

nominative object -> telic, indefinite
explicit accusative object -> telic, definite
partitive object -> atelic, *

This does not seem like an all too impossible way for a three-way differential object marking to appear.