I have a few thoughts...
1. Part of this is due to the fact manufacturers are trying to draw out maintnance times by adding larger volume oil sumps, fancy oils better machining and such and while these are good things people are more likely to get complacent with a 10,000 mile oil change than if they know they are just supposed to go in every 3000 miles and get an oil change.
That's why there is an oil change light. And no, it's not just based on mileage.
3. Most of those really long maintenance intervals are for drivers in the absolute best driving conditions, very few drivers should ever go that far as most everyone has something that drops them into the "severe service" catagory, the salesman just wants to point out the long interval not the normal one. Again though it still comes back to customer needs to take responsibility to look up the info.
Again, the oil change light takes this into account. All he had to do was get his oil changed when the light cam eon. Short of doing it for him it doesn't get any easier to remember.
5. You can get low mile long block engines off car-part.com as low as $2500 plus shipping, my labor guide says 17 hrs for a long block swap, at $100 (I charge $80) hr thats $1700 add in antifreeze, oil, filter.. maybe $100? $2500+$1700+$100=$4300 ish? May need to throw in $300 shipping if you can't find one locally... the dealer is not the only place to get it fixed.
The dealer is the only place to get it fixed under warranty and the factory doesn't go junkyard shopping for your warranty engine. Hence the high price listed. Can it be done for less?
Yes, but there is no factory warranty involved there. 
