I'm not necessarily the biggest fan of the TIOBE index, but in this case I'll cite it, as it is "close enough" I think. Ruby is #13 right now, which isn't bad. And while I think TIOBE has some warts, I think it's safe to say that anything in the top 20 is fairly successful, and anything in the top 50 is "successful" to a certain degree.
http://www.tiobe.com/index.php/content/paperinfo/tpci/index....
You do know VMware/Pivotal pulled their support for Groovy in March this year and no-one else stepped in, don't you?
I do, but I also know that Groovy is becoming an ASF project[1]. So we'll see how it goes with volunteer support, and perhaps a few paid people here and there from companies that use Groovy.
Groovy has lingering problems in migrating to builds.apache.org, see [1]. Some of the Groovy despots from Codehaus times (I wouldn't know which ones specifically) are keeping some computing machinery physically separated from the Apache infrastructure to run their own build processes, going against Apache guidelines. Some of them also have control over the groovy-lang.org domain (again, I don't know who). I suspect Groovy won't ever become an ASF project, but instead just sit it out in the incubation system until the former Codehaus Groovy despots get a better deal where they don't have to share their control democratically with the ASF. They managed to keep Groovy in the Java Community Process for 9 years before being booted out, all the while using the JSR-241 to promote themselves, so they'd think nothing of leeching on Apache's incubator for just as long before stirring up conflict later on to get booted out when it suits them.
BTW, that link [1] to Nabble's Groovy mailing list archive was recently redirected to an embedded view within the groovy-lang.org website where they can collect IP addresses, and all that implies -- another indictment of the Groovy despots longstanding intention to control and instead of sharing.
[1] http://groovy.329449.n5.nabble.com/Jenkins-Groovy-Apache-etc...
So? I'm not making a claim that a language needs adoption on that scale to be considered "successful". To me, Ruby, PHP, Python, Groovy, Scala, Clojure, etc. are all very much "successful". The languages I think of as being less so, would be things like Nice, Fantom, Frege, Forth, Modula-3, Rebol, etc.
History shows that the answer to that is a resounding yes. Aside from a couple of scripting languages (BASIC and Python), there have been exactly zero successful mainstream languages without a large company behind them. Scala, Clojure and Groovy are doing fine, but their adoption is one or two orders of magnitude less than the mainstream languages (Java, C, C++, C#).