Just of few comment on you insite
1. Most people will agree the average economical life span of a truck is 10-12,000 operating hours - just do some Google research - there are some good articles that validate this point. At an average useage rate of 1600 operating hours per year (single shift operation) that equates to 6.25 -7.5 years.
2. In the US it is most common that the leasing company is on the hook for the residual value at the lease end, unless the selling dealer wishes to guarantee the residual - most do not.
3. That makes sense but if the end user opts to release new equipment then rates stay pretty much the same depending on the interest rate change & price increases on new equipment.