I think the OLED model will lead to rising Switch sales, but I don't expect wonders at this point of its life cycle. Most people should buy the OLED model who would have bought a Switch anyway. There aren't that many people who already own a Switch and will upgrade to the OLED model, I guess. And mainly these people would cause rising sales numbers. It would be a completely different case if the new model would have had more power. There's no reason to upgrade to the OLED model, if you usually use your Switch in TV mode.
I expect Switch doubles sales at OLED opening week (between 600-700k) and sales should stay around 400k (a bit higher than currently) and rise until Black Friday. There's actually no real system seller announced for the remaining year. Next year should be different with Zelda, Splatoon, Pokemon Arceus and Bayonetta (well, Bayonetta shouldn't move that much hardware).