Wow.
When you calculate the odds of making the playoffs, 100% probability is absolutely the same as being certain. If there is a single path (set of game outcomes) that leads to a team not making the playoffs, the odds of them making the playoffs are necessarily less than 100%. That path may be incredibly unlikely, but that doesn't matter: there is still some non-zero probability of it happening.
If we're talking about the existential sense, in that they may not make the playoffs because global thermonuclear war causes the playoffs not to be played, then sure, whatever, but that just means that the probability is less than 100%. And I assume that's not what we're talking about here anyway. We're talking about the conditional probability that, given that the playoffs are played, the Cowboys will be in them. And that probability is less than 100% right now, and it will be less than 100% after tomorrow's game.
"Almost surely" is not a probability of 1. It's a probability of less than 1. That's what the "almost" part means.
These calculations are not difficult. And I can assure you that the number Burke has calculated is less than 100%. Not much less, but less. Because he knows how to do math.