anytime BYU beats a P5 flagship state-sponsored institution (especially, when it's a blue blood program on their field), it's one to savor and put in the memory bank.
And just like last year's win at Wisconsin, the win at Tennessee may be the difference maker for BYU's bowl eligibility.
That being said, if BYU can somehow split its next two games against USC and Washington, 8-4 seems a fairly realistic scenario (barring significant injuries), given where BYU is right now as a program (from my vantage point, BYU is still too inconsistent overall and not good enough offensively to avoid losing a couple of its G5 games).
But in the somewhat more likely scenario that BYU loses its next two games (especially, given how bad BYU has been at home the past few years), I think they'll be fighting for 6-6 again (if they get swept at home by USC and Washington, I think it will translate to an additional G5 loss as compared to the scenerio where they split those games).
And if BYU were to somehow sweep USC and Washington . . . well, that's a fun fantasy to dream about.