[rimmjob]

java is the most used language right now and using the jvm gets you access to all of that infrastructure. it also makes it really easy to port code to linux, macs, windows, phones, tablets, etc. practicality is one of the stated goals of clojure and the jvm adds a lot of it. aside from the lack of tail-call recursion, it doesn't really bring any real downsides.

on topic: theres no reason that only one can succeed. it's like asking whether linux will beat windows or whether hamburgers will beat hot dogs. they both bring different things to the table and target different people. scala has more common territory and thus more at stake with clojure than arc does. the only thread of commonality between arc and clojure is that they are both lisps and that is hardly the most important thing about either of them.