While 70 series are cool mostly because they are exotic in the US, the supply is only growing year by year, thus the values are destined to flat line or depreciate. 70 series are not collector status and probably never will be unless you have some real odd configuration or survivor and a 70 series collector buyer (unlikely). Most coming into US are hiding repairs and sellers are asking way to much for what you get. Time to take off the rose colored glasses.
Furthermore, the craftsman and quality of design of the 70 series is not one to allow these vehicle to last 50 years. The paint jobs are crap, they leak like screen windows, rust like crazy because of cheap steel and poor drainage, and are severely under powered like other cruisers.
Ask our Canadian friends to the north who have been importing 70 series 10 years longer than Americans - how has your 70 series depreciated since buying it?
Ten years in Canada definitely will cause a vehicle to depreciate. Typically because of deteriorating condition, not necessarily dilution of market. However, I don't agree that the price will generally drop over time, especially for the nicest trucks. Nice trucks become harder and harder to find, more rare, not less rare. I've sold a few trucks that have later sold for more. Very nice trucks will hold value in the US. And there actually are quite a few LC collectors picking up 70's. On the other hand, you don't have to be a collector to appreciate the greatness of the 70 series!
Anyway just my opinion.
To the OP, would be happy to talk 70's if there's anything I can help with: Land Cruisers Direct - Vehicle Inventory