It’s all speculation, but if they really decided to exit scam and leave the $40k behind, there is a chance someone deposited a big amount and they just unplugged everything to keep the coins. Remember that coins from big hacks and exploits were being mixed on CM, so there is a chance someone stole a couple mills and tried to mix them through whirlwind. (Pure speculation)
Discussions about the mixing service started on August 9th and so far there is no warning that there are problems with the withdrawal, @sam00 was the first one to report about withdrawal problems and from that date the number of people who deposited is very small although there was no warning about withdrawals problems on WWM (and still).
this means that Promotion of the service was not enough, and until now, unlike the members of the signatory campaign (most of whom did not make withdrawals), no one reported about loss.
I seriously began to think WWM was dead for a while and their budget was limited for about 3-4 months, so I believe that scam is about 3 bitcoins or less than half a million dollars.
The thing I didn't understand was why they didn't ask to withdraw the $40,000 a while ago?