Valhalla was a huge success commercially. Made over $1 Billion in just over a year, 20m players in it's first 2 years. Probably sold around 15m in 2 years. While I don't think Shadows will hit that mark and I expect it will "fail to meet expectations" for Ubisoft it's still going to sell well. I'd be surprised if it doesn't hit 10m lifetime.
My answer to the question in the title compared to the poll is different. Yes Ubisoft is in danger.