In practice, that means that it never makes sense to buy any lens until it has been on the market for at least a year or two unless you're actively making a lot of money with your lenses, and it rarely makes sense even if you are.
I would like to offer an alternative assessment: If you know that the lens price will drop 1/3rd in the first year, you can simply decide if this "rent" to own this lens right now is "worth it" for whatever reasons.
There will be enough people who will pay, look at all the "I was happy to pay $3500 for my 5d3" posts around here... it doesn't matter if you try to evaluate your personal amateur fun value, or the professional return of invest. This cost is just another small part in the "total cost of ownership" for the gear that also includes insurance and repair costs.
Canon is not around to make friends but profit, and the current situation that you can re-sell an L lens at same or above value is a complete irregularity when it comes to technology products anyway, if you're looking for a steady investment with some recreational use look at buying a good oil painting :-)