All very logical, but I think a short production run + high price point for SOH = little hoarding.
The comparison to modulars is interesting: Some facts to chew on:
1. There have been five advanced model Statue of Liberty (2000), Eiffel Tower (2007), Taj Mahal (2008), Tower Bridge (2010), SOH (2013). Five since 2000, but roughly one every two years.
2. How many modulars have there been, and how often are they released? 9 modulars total, one per year since 2007.
3. Sets with a lower price point typically have higher production runs. I would guess there are many more sets of each recent modulars produced than SOHs (as of today).
Add this all together and I think it's safe to assume there are many fewer SOHs than any of the modular sets.
I agree there's a demand component this completely glosses over, but in recent past, it seems like the sets with lower production runs have determined the fastest climbers - see Town Hall - unlike the most popular sellers (see Grand Emporium). That's why I think SOH will grow quickly if it retires soon, and have a much higher ceiling than any modular.