Some people will without doubt be successful with dotmobi, irregardless of the tld's success. The same can be seen with other tld's...
But for those of us who have mostly parked domains (i.e. me), success is a different matter. And most domainers aren't even moderately decent developers -- I know at least 10x as many that are in the same boat as me, mostly with parked dotmobis or inferior quality developed ones, as I know with kick ass sites like Vcool.
I agree with Garrett -- No big guns, no dotmobi default -> no future, other than for the very best, and LLL.mobi, NNN.mobi which will likely still be valuable due to their scarcity.
Dotmobi has never had a purpose -- let's face it. If Verisign switched the rules tomorrow, stating that all dotcoms must be mobile compatible... All of the sudden all dotmobi are worthless. If Opera, Microsoft, Mozilla, et al. were to put their differences aside, and all work collectively on a mobile browser, they could probably come up with something that would put mtld to shame.
Dotmobi's purpose lies in it's guarantee of a mobile compatible site -- but only if this guarantee is enforced, which we do not yet know the extent of and even how or when it will finally be enforced. Sure, we can give dates... But how well has that worked with the RFP? For all we know, it could be next year before they start enforcing... Or later.
I'm not trying to be pessimistic -- rather, realistic. Dotmobi does not depend on compatibility, it depends on adoption by these 'investors', which seem like they haven't invested all that much (relatively speaking).
To put it all in perspective, about a year ago, headlines were made in Manitoba, Canada when Bill Gates announced a donation (I guess we could call it an 'investment') of $20 million to fund AIDS research at the University of Manitoba. Now, would we call Bill Gates an 'investor' in the University of Manitoba? Of course not -- mtld has alot of marketing BS that is really starting to piss me off. The people running multinational corporations aren't going to be tricked into investing in dotmobi because some 'marketing professionals' claim investors such as Microsoft.
A first step would be Microsoft actually using dotmobi. Until then, this is just a donation -- nothing more. Would you consider me an investor in the Red Cross, every time I pass a few dollars their way? How is this any different, UNLESS we default .mobi... I see this as necessary for the success of .mobi, not only for widespread adoption of the extension -- but for countries where unlimited bandwidth is still not available. Of course, WiBro/WiMax, 802.11x may alter the situation.
Defaulting it -- and yes, this was the case with dotcom early on, is a clear indicator that Microsoft and the telecoms are investors, and not merely donating.