The first thing i am going to bring up here is Nynorn nominativ.
Not so long ago, i got to think about the oldnorse ending -r, which in danish turn out as -er. I found out it always turns out as -er, that is the sound law. However, the reason why we dont have "hester" but "hest", is because the accusative replaced the nominative case in danish. So where oldnorse also had -r in accusative, danish still got -er (bønder, fødder, hænder).
Next day i talked with my teacher about it, he told me i was correct, and there not so long ago, a lady had investigated the nominative in gammeldansk. Her studies shows that already in gammeldansk, the accusative had began replacing the nominative, and the nominative got a new function. This function, has in modern danish turned out to be like this "en grimmer mand, en slemmer mand, en flinker fyr evt. It is not used very often, and to me it sounds like "en flinker fyr" is adressed to a certain guy, still unknown, while "en flink fyr" could be any nice guy.
Anyway, Her research has been printed in a book, and i will try to get my hands on it
And i will try to see if this works for norn too. I known norn has relics from the real nominative, but so had gammeldansk, so if it is like danish it is an older stage than danish yes.
But yeah, what do you think of the idea?