There's a curious effect with high renewal rates. It is similar to the idea in Economics of the sunk cost fallacy but it is slightly different. Some of the NGTs with higher renewal fees actually have stronger renewal rates because people are likely to value these domain names higher than heavily discounted or free domain names.
The other aspect is that "parking" is very difficult to measure and a lot of the stuff that appears on the web, such as the NTLDstats stuff, is woefully inaccurate.It was showing that .LOAN was 70% parked until recently. The reality was that the active usage rate in the gTLD was less than 1% based on the latest survey.
There is also a major problem with renewal rates based on the registry reports. The blended renewal figures from the registries tend to be more accurate than the monthly registry reports.
The geography of the gTLD also influences renewal rates and usage. If the gTLD's registrations are primarily in a country with a volatile market then that gTLD will show the same volatility. If a gTLD's registrations are primarily in a mature market, then that it will follow that market's dynamics. Some of the large NGTs are not single gTLDs but rather hybrid gTLDs made up of a stable market with good renewals and a smaller market based on heavy discounting. There is a high turnover with the discounted registrations.
There are some worrying trends with some of the current round of new gTLDs and a few of them have failed. Many of the Specification 13 brand registries have already terminated their gTLDs. (
https://www.icann.org/resources/pages/gtld-registry-agreement-termination-2015-10-09-en ) Some of the open gTLDs are definitely not doing well in terms of registrations and usage. A few of them have been taken over but only one, .WED, is frozen in EBERO. Financially, it is difficult to see some of the low registration volume NGTs surviving.
And there are even people in the ICANN community talking about a new round of new gTLDs. If anyone ever wondered where the people from the Sub-Prime debacle ended up, there's a good possibility that they became new gTLD consultants.
Regards...jmcc