I'd say our customers would think we're slow to support new Java versions. But I'm also pretty confident that they've never heard of Clojure and probably not even Scala. I added support for Groovy a few years ago and it's received very little attention despite the fact that it often makes it possible to apply code changes immediately and avoid the long (2-3 minute) application restart time.
Our customers are mostly fortune 1000 companies, the people we deal with are not very technical and almost always outsource all of their development work overseas. They're also very good at finding outsourced developers with minimal skill sets. So a language with a smaller pool of developers would probably be seen as a negative.
We could but it would be difficult. Our product requires that our customers subclass our Java classes to implement their custom business logic, and sometimes it's necessary to provide the source to our base classes for reference. Sending a customer some Clojure code and expecting a Java developer to know how to handle that doesn't seem reasonable.
one can also ask the question whether its you that want to continue coding in java, because you think in java, or because you want to avoid learning something new. But yeah, if the customer don't grasp Lisp, you are pretty much settled with java.
If one were to ask me that question I would respond by saying that I have been programming in Common Lisp for many years and would gladly switch to any lisp, especially Clojure, if it made sense for our business.