Having a 'nice' phone number was really important at some point, easy to remember. Now we all have address books.
The DNS is nice, it works well and I'm sure that it will continue to work well for a long time. But gtlds are the same as area codes and I have absolutely no idea what having an area code of '1' would mean for a business that is not in the United States.
.coms used to be pretty much the standard, I see many more people launching more and more successful businesses on non .com domains. Given enough time (ok, probably a lot) the weight of a .com will likely reduce to the point where it is just another identifier. Maybe we'll all be scanning QR codes, maybe browsers will in fact hide the domain, maybe at some point you'll never type on in again.
I'm not saying the DNS will die completely, I just think that the length of a domain will not be as important any more. But if you brand happens to be LL then you'd better have LL.com, that probably is a given for the foreseeable future. Weight Watchers, World Wildlife Foundation and World Wrestling are obvious contenders but even they were not interested. So now some Chinese company will run with it, I'm curious how they will fare and what they will do with it.
For me a domain is a requirement, just like hosting is a requirement. Camarades.com became an instant hit and it was very hard to spell. Google wasn't even a proper word before it was used as a brand (they miss-spelled googol) and now it is almost a verb. Facebook is an ugly juxtaposition of two otherwise unrelated words. If ww.guru is your thing and wwguru.com is free then for the $10 or so you really should just take it. But if the .com is taken just ignore it and find another one. In the end a domain is an identifier, it is the service behind it that matters most. So if you plan on starting an escrow service it helps if you can obtain escrow.com. But if you can't I would not worry about it, there are tons of options.
I've yet to see a service succeed just on the strength of the domain, and I've seen plenty of services with great domains fail. A good domain can help but will not be the defining factor of a success.