Actually, John, Zeiss was never a camera manufacturer, so they have always been a third party supplier of exquisite optics. Being "third party" does not imply "inferior" unless you want to read it that way.
As a point of fact, they have never left the market, not been "in & out." Zeiss has been around as an optics company for 180 years. I'd say that's pretty good staying power. They are an older company than Leica & a much larger one with a much more diverse application of optics, greater research facilities, & far better financing. If I had to put money on which company would be around longer, my money would be on Zeiss.
I love your turn of a phrase >". . . go over like a fart in church." I'm still laughing oveeer that one.