Java's key promise. And may run so slowly on 16-bit Windows, they become unusable. I'm still hoping we'll end up with Java virtual machines that are consistent across platforms, but right now we're still just wandering around. Businesses will rewrite their applications in Java. Of course not.
People hate to throw stuff away.
People will do everything new in Java. Every language has its strengths. Java is secure. It is also more restrictive. Java is an open standard.