I think that 1 year is plenty for the buying public to forget the N7 disaster. I see pros and cons with your suggestion. I personally really like your idea but the downside I think is that it is an obvious attempt to rename and disassociate from the Note 7. I think many people will see through the name and realise it's another Note with a different name.
If Samsung did that, then I think it's a BIG mistake to call it a "Pro 8". If you call it a Pro device, then it has to be just "Pro", indicating the first iteration of a truly new line of product. Then to justify renaming it, you have to do something different that the Note serious didn't do. Introduce some new features to truly justify the new badge. Otherwise as I say, people will just roll their eyes and see through it. And differentiate the new serious from the S series, so that it does not suffer the criticisms that it's just a bigger S phone with an S pen.
Let's say you introduce the first Pro series and you give it something exclusive like in the Pixel phone, such as unlimited cloud storage for photos/videos, on-screen customer support etc. Something the S series doesn't have. And it has to be something the S series will not eventually get, for e.g., iris scanner.
But I really like the idea of a Pro series. I think that's a great idea.