Would it make things easier for searchers? I’m not sure. After all, search engines have been designed to find information with little regard to the actual URL it appears at (but it can have an effect on how well that page is ranked).
It seems to me that power-users, those that understand what the URL is and how it denotes a hierarchy of information, may be the only ones to benefit from this – certainly in the short to medium term. That’s no reason to not do it, though, and I’ve tried to do something like this in recent projects I’ve worked on.
Will it happen? There’s no reason why not (I’ve made no secret of the fact that I’d have mod_rewrite’s babies if I could), but it will take a lot of work to educate people regarding the technologies and tools that can make this happen – and the reasons why it’s a good idea. In some ways it’s like the campaign for web standards: we have to be realistic and acknowledge that it’s still a minority movement despite there being clear reasons for using them.
So, for me, I’ll bear this in mind whenever I do a site (I love clean URLs anyway) but maybe we need Dan or Tantek to start MacroFormats.