We'll see them again most probably in season 6 (if there's gonna be one). For S5, it's already been said we won't see them.
It's true that no ships can match the fire-power of the Asgard weaponry, but Earth has only 3 ships, and when they get in trouble, we usually see that they get damaged or neutralized, making it an opportunity for their enemies to try and win the battle (not that they're having much success), and that's how it's made to look like not invincible and yet interesting to show.
And we did see Michael rise to power... just in an alternate timeline. He's a skillful adversary already, but in these things, we'll never see the bad guys win wars... maybe battles (Prometheus and Korolev destroyed by the Ori), but never the war, because it would mean the show's actually ending, and nobody wants that, and even if it was not to end, nobody wants sad/losing endings. It's the business.
PS.: Thanks Coomdoom, I think I remember it now... he should use a PSP, they're more versatile.
