The most recent plan was to use e.g. x.y!z for (x y 'z).
I almost did this for the current release but left it out because I wasn't sure. I tried rewriting some code using it and it didn't really feel shorter. Whereas : as composition really does make programs shorter.
My current plan for syntax is to use chars in the middle of what would to earlier Lisps have been normal symbols. Restricting the introduction of syntax in this way keeps the Lispy feeling. So foo_bar for example will eventually mean something involving two symbols, foo and bar. But there are only so many characters I can make special in the midddle of symbols, and I don't want to use them up unless I'm sure.