"When Python 3 was released in late 2008, it was not backward-compatible with Python 2. The plan since then has been to sunset v2 once enough developers made the transition to v3..."
The same has been the case with PHP. It's absolutely crazy to make new versions of a language unable to maintain older code without a huge burden of rewrite. By all means add improvements, but deprecate rather than eliminating their predecessors. Maintaining the language should take second place to maintaining code written in the language, simply because the code it what its all for.