I agree that there will always be a large number of mobile phones that will remain with keypad entry, so they can be kept small. Therefore short domains are attractive, especially single-touch letters. The 3 digit single touch letters combinations were the first to go.
The important thing for the future is to 'follow the money'. Think of the value of the companies we have as partners here. Microsoft and Google in the same bed? Do you think they might be looking for a new platform for ad revenue?
The phone manufacturers, Samsung, Noika, Ericsson, want to create a consumer need to replace their old phones. In addition, the service providers will benefit by additional time use.
The general public is not yet aware of .mobi, but I expect that we will see a major advertising push by the sponsors. The power of the combination of these world-wide companies is enormus. The will create a 'need' in the public's mind.
This will all take some time, and development of websites that people want to visit, but it is coming. Be patient, mobi lovers, we have a bright future.