- I created this as a discussion piece: should we include stacked modals such as this? I say yes: they're not sum-of-parts, because most speakers cannot sum those parts.
- I would have liked to include, among the context tags, that this is nonstandard or even proscribed outside dialects, but context reached its parameter limit.
- The conjugation might could be included in a more standard way.
What's the evidence that this is from North Germanic? Maybe there is something, but at first glance it seems unnecessary. I suppose that in Old and Middle English, when modal verbs still had infinitives, these constructions were normal, as they are in all other Germanic languages. So when the infintives were lost, some dialects started using the remaining forms instead, with a tendency to "agreement" in tense (may can, might could, etc.). Exactly the same development can be seen in Afrikaans, where this is standard: