i like some of these ideas, particularly lexical. org already has a lot of syntax. i am leery of introducing yet more heterogenous syntax to org. key word heterogenous. i don't mind more features if it is always using the same syntax framework and thus can take advantage of everything else that uses it. key word framework.
thus, i'd propose a single syntax framework that takes care of future syntax. a syntax framework like $[annotation ...] where ... is specifiable as a lisp lambda list or similar could also be used for other features, including long-form emphasis. i don't think long-form emphasis is a bad idea at all. it allows export back end independence. i only think it is bad if it means introducing heterogenous, non-framework syntax. a single framework takes care of future features too. and as a bonus it allows future subfeatures. for example, there is no need to implement authorship in annotations until we decide we want them later. when we do, just add a keyword option: $[annotation :author "joe"]. and yet another bonus is that it could be used for user-defined features. all without adding heterogenous non-framework syntax. === i would need fontification to be able to fontify inline footnotes that have more than one paragraph [i.e. have blank lines in them, which is currently not allowed in 8.x org export. fontification currently and always has fontified them correctly from my perspective i.e. by allowing multiple paragraphs].