The odds of every game ending in a loss is the same as the odds of every game ending in a win. They're opposite sides of the same coin.
You're going to need to clarify this. Do you mean for any randomly generated team? I might agree with you there. I haven't looked at the historical spread. But that isn't at all what this discussion is about, so I'm assuming you mean for a specific team. And that would be 100% wrong.
And our disagreement is probably due to the "scope" of how we're wishing to make these predictions. I think you're going from a more holistic approach and seeing that a) we've overachieved according to the PF-PA differential and the projection for wins and predicting b) that we're going to eventually underachieve, which isn't what we want.
I'm taking a more specific approach and treating each season as separate from the season before because I think there are so many extraneous variables that factor into wins and losses that can not be controlled, so we can't look any further than just one year.
For starters, I never said or implied the bold comment. I was talking about
regression toward the mean, which is entirely different.
The disagreement lies in the fact that your second paragraph is just not true. Are you honestly telling me that the result from last season - a season against likely the same teams, with about 75% the same rosters - is completely uncorrelated to the result of the next season?