User blog comment:Xilinoc/Ch. 553 - Frozen Cross/@comment-10371091-20131017043832/@comment-11051098-20131017193811

There's still 22 Sternritters + Yhwach from the Wandenreich, + an unknown number of Soldat. The Gotei 13 has about 20 captains, former captains and Royal Guards + Ichigo, strong enough to fight them.

Only 3 Sternritters have been shown in battle in the current invasion. Even though the captains have got their stolen Bankais back, and Kisuke's pills apparently have made all Bankais immune to the medallions, we have only seen a small part of the Sternritters fight yet.

Haschwalth said that Yhwach's order was to "instantly exterminate the entire enemy army". So no, it's not over yet, it will take time.