All languages (like any system) will have cruft, after a while. Is the solution really to do a periodic break with backwards compatibility for purity reasons, Python 3 style?

There should be a better way?!

What about a low level machine like Java/.Net and just let the next language evolve on top of that -- so old libraries could run? (Maybe there could be Xcompilers for Ruby/Perl 6/xxx to the Perl "bytecode", to take advantage of CPAN?)