you'll always be able to survive on one language. especially such a huge language that will leave a giant legacy footprint if another language becomes more popular. the question is, will you, personally and financially, prosper. you want to do more than survive.

it won't be easy, but its possible. check out grails and seam to push yourself into the rails-like environment running on java. i really like grails.

or, you can just do like others and learn rails or python.