I think what will determine whether or not .mobi takes off is...
1. do the sites have useable content
2. are the handset companies using .mobi as the default search engine
3. lower priced phone internet service
4. marketing, marketing, marketing by the creators of .mobi
Now, the other thing to consider is there has to be user friendly site builders so people who don't know anything about code can post their site. At first i thought the reserved/premium name list was a bit of a farce, but i now think that .mobi is trying to ensure at least premium names are sites with useable content (not just parked because of speculation). Otherwise, users will not keep coming back to the sites.
I am wondering however, if there will actually be a device, a mobi that will be the next generation of the pda/phone/computer/game/music/movie player on the go.
I think the landrush will be a bit of a mess; it reminds me of a name drop where all the registrars are competing to get the name. I wonder how many inside deals there are.