If you want to demand perfection, then Clojure isn't going to meet your standards (what would?).
The issue here is that, based on the way they (particularly Rich) talk, we can expect they will not do Bloody Stupid things like the old Python 2->3 changeover. Things like big, breaking changes that require architectural changes to keep current, or break all the available tutorials.
If the problem can be fixed with a macro or single function (like a change to plus behavior) it is an irritant, not a threat to productivity. That is not a concern.
