Another potential risk with very specific niche gtlds is that something can come along and change the game. Something that has nothing to do with domain names can still come along and affect the niche extension. The Apple iPhone and its .com button along with how smartphones easily rendered a website on a phone was a big hit to .mobi.
The .menu extension has already been delegated and four companies are vying to run .restaurant. Tech Crunch did a post yesterday which expanded on something I saw for myself while looking up a local Italian restaurant on Google, earlier in the week.
Frederic Lardinois wrote for Tech Crunch:
Here is a small but nifty update to Google Search: if you ask it to find a restaurant menu for you, it will now often just show you the menu right on the search results page. Try this for a search like “show me the menu for fogo de chao” and the menu will be right there.
Now of course this doesn’t mean that these new extensions don’t have other ways to be utilized, but its just a reminder that Google continues to make tweaks and changes that can affect the best laid plans of niche gtlds.