Whenever I see things like the linked presentation (turns out I've seen it before), I can't help but think it's a solution in search of a problem. Simple parsing & evaluation models lead to expressive languages, and (I intuit) that's why their notations stick around despite people's efforts. For time immemorial, projects like these try to take a simple, consistent notation and pile on an abominable number of special cases with line noise more offensive than just parentheses . It's not only unfitting for Lisps, but it's limiting for language design. There's only so much you can do with abbreviations, but soon enough there's feature-creep. I see that in his estimation (http://sourceforge.net/p/readable/wiki/Retort/), the special cases are sparing. But really? He needs three kaleidoscoping levels of syntax, knee-jerks to using the different brace types to supply soothing Algol-isms, introduces an indentation scheme that needs clarification regarding edge-cases with traditional syntax, and still finds a way to need special characters with special rules for "advanced" features. I guess we can agree to disagree...
In the end, I think it's a mistake trying to make Lisp notation something it's not. Much better is trying to improve what you've got within the structure of the language, like Arc turning
(let ((a 1) (b 2))
(+ a b))
(with (a 1 b 2)
(+ a b))
People are drawn to the idea of finally making Lisp "accessible" (I guess fixing society's use of infix notation is harder :P) while still retaining homoiconicity. Yet most seem to forget that homoiconicity requires simplicity, not Lisp syntax. People get stuck thinking inside the Lisp box, but again, simple parsing & evaluation models lead to expressive languages. For instance, combine a stack machine model (http://docs.factorcode.org/content/article-evaluator.html) with a simple parsing algorithm (http://docs.factorcode.org/content/article-parser-algorithm....) and you get a homoiconic language. Of course, it's a postfix language, so its math is unparsable to mere mortals...
 I admit he has a point about existing abbreviations that I'm simply used to, like quote/quasiquote/comma/splice and dotted lists. I think where those notations have stood the test of time is that they're subtle. I can use the quote family and the code still looks like Lisp, instead of looking like Lisp trying to look like C.
I think some moderate use of parentheses is okay, but I don't really like using them everywhere. Though, I wouldn't really mind an Arc dialect that had good syntax for functions and a Nulan-style type system, even if it did use parens.