Very good article and I experienced this very thing in 2012. Lost two major clients of over six years, as desperate consultants had been hitting them hard and promising the Moon if they'd go with them.
Panic set in and I went through a lot of what was outlined in the article.
On Christmas Day one of the clients called me and they were losing $40k a month in revenue after firing me in June and going with someone else. They are now back.
The second one has called me and setup an appointment this week to discuss my taking the account back over. I guess the Moon wasn't that good.
It did wake me up that I have to concentrate on getting the front door open wide again, because the back door can get larger in a slow economy. If you are a good consultant, you also have to keep the faith and stay positive. Learn from these bumps because it would be very easy to go into a tailspin from this.