Rumours of JetsGo's demise have been floating around for quite some time, but I didn't know that the problems had been so serious.
The airline had a number of maintenance issues with the MD-83s which gave the airline quite a reputation for delays, and the service levels onboard simply did not match that of fellow Canadian no-frills airline WestJet.
Whilst there was a huge void in capacity when Canadian was snapped up by AC, and the subsequent demise of Royal/Canada 3000, WestJet has expanded fast enough with their modern fleet to partially fill that void.