How old can a vehicle be before clients don't want to ride in them? Say you picked up a couple of low mileage '09s or something that had dropped in price...at what point do they become undesirable? Age or mileage/condition?
As the owner of two vintage hearses, both of which had less than 20k on them when I bought them, I can tell you that in the funeral business, the vehicles are the funeral director's calling card. These are what you see with the nameplates in them as they amble down the road. Generally, whenever Cadillac, or Lincoln, changes the body style, the previous vehicles drop in value by a significant amount. I paid near nothing for vehicles that if they were DeVilles, or Broughams (or in the case of Lincoln a Conti or Town Car) would have brought much higher prices. In fact, I rescued both vehicles from a certain trip to the crusher.
The MK-T pictured really doesn't look that bad to my eyes. The mid 80s "daschund" look Cadillacs were much worse.
One of the problems with building funeral vehicles is cost. My 1975 Cadillac Superior Side loading hearse had a cost of over $35k in 1975. That was a STAGGERING amount of money for a car. My end loading 1976 Cadillac S&S Victoria Landau was over $30k. Again, a HUGE amount of dollars. Both are "Z code" commercial chassis vehicles, NOT converted sedans which is the way things are built now.
Up to the end of the 1984 model year, Cadillac supplied custom coach builders with what was known as a "commercial chassis" and you see this reference in the Owners Manuals all the time. It was a long wheelbase (longer even than the Fleetwood 75 Limousine) chassis with every heavy duty component that Cadillac could muster. After 1984, Cadillac supplied "decontented" sedans. Because there was no longer a long wheelbase chassis, coachbuilders were left to their own devices to produce vehicles that their customers wanted. Some made very credible attempts, but others were, well, not so successful. The "cut n splice" method used now doesn't always make a vehicle whose lines "flow" correctly.
The Town Car, and the late, lamented Brougham, had lines that did well when put into livery/limousine/funeral guise. But the other models, not so much.
As to how well the MK-T platform will hold up, that's anyone's guess. The Town Car has a 300k mile life. The old Brougham was similar. I'm not sure how the DTS based and MK-T cars will do. They may just surprise everyone and hold up, but as I've said elsewhere on this forum, I'm NOT a big fan of FWD/unit construction. I'd much rather see RWD/body-on-frame.
Time will tell.