Their fleet is pretty much gone as are their shipyards.
While they did wipe out an Extremis level Ork planet plus a few lower threat level ones there are still 3 other Extremis level Ork worlds in our area plus some other lower threat level ones.
They used to have several thousand ships before this but they are pretty much all damaged to some degree now.
Given the fact that repairing their shipyards can take up to 6 Bonesinger actions at once for an unspecified amount of time while fixing Meros's engines could only take up 4 Bonesinger actions (we spend 3) the damage must be truly devastating since Meros is significantly bigger than Arach-Quin going by the
images Mechanis posted.
Given the fact that Meros took around 3 turns (repairs started 970.M29 and were done 986.M29 so ~16 years) to fix at 3 Bonesinger actions a turn repairing Arach-Qin's Shipyards if they take a comparable amount of time and investment (let's say 3 turns and 4BAP a turn to reflect the 75% investment Meros got) that would be equivalent to most of a turn's worth of our BAP (12/15).
We're supposed to have comparable Industrial Output to a Major Craftworld so a Minor Craftworld like Arach-Qin would probably take much longer to fix their shipyards and even longer before they've repaired their ships.
Not a particular pleasant situation to be in given how close they are to a Major Ork Warlord and Freeboota hub.
Edit:
Just took a look at how long it's taking to repair their ships and one of their battleships was so badly damaged that it'll take us
8 Turns to repair it from start to finish.
I know we're only spending 1BAP to fix it and their other ships but just imagine how agonizingly long it would take them with their Minor Craftworld BAP output.