Hello! Is audio required?

I think so

yes audio is required due to splicing.

Ok thanks!

what will happen to this when the 31th of march comes?

everyone dies

No one knows the answer to that question. We can only speculate that it will either just stop production and be sold through retailers, or (my wishful-thinking theory) they will sell them as stand-alone titles on the Nintendo eShop (which I hope they do, but knowing Nintendo, probably won't happen).