Great idea! I wish the maintainers & implementors of other languages would follow suit.
Doesn't it depend on your goals? For example, I expect Haskell to be a hotbed for experimentation for a long time to come. In fact I think people choose Haskell because it is continuously evolving.
I know that I picked Clojure recently not just because of it's features - I picked it because it _wasn't_ stable, it _wasn't_ all figured out. In fact, as part of the community, you can actually contribute a hand to it's future.
It's just Python has matured to the point where people would rather experiment with it's implementation rather than it's syntax/expressivity. It also has to do with the fact that this looks like part of a growing effort to make Python _immensely_ popular - going head to head with the likes of C++/Java.
As far as I'm concerned that's a good thing for Python.
But it does mean if you're looking for new ideas in PLs you'll have to look elsewhere. But it's not like there's a lack of excellent and popular candidates these days.
To me that's just part of the beauty of Common Lisp. While it is rather ugly in some places, it has these nuggets of just pure gold.
(I actually do not know scheme well enough to say. Are such complicated macros possible in it?)
(And I would not want to do loop in Scheme. That's just too imperative. Interestingly Haskell's special syntax for Monads and its lazyness makes the need for most macros / special forms go away (though not for all, and Haskell has plenty of syntax on the surface).)
Consider that Paul Graham, the author of the fine book "On Lisp", chose PLT Scheme to implement Arc on top.