(a) On non Sun JVM-supported platforms Sun would always point to other VM's (eg, hardware support for JVM bytecodes in ARM, etc). Also, they would quite happily discuss the benefits of using IBM's Linux JVM.
d) The Java ecosystem has grown because of the diverse range of vendors. It's easy to make an argument that JavaEE only survived the .NET onslaught back in ~2002-2005 because of the high-quality and free implementations from Apache. The current biggest growth market for Java is in non-traditional areas (eg, Google's product: AppEngine/J, GWT and especially Android). Oracle should work with these vendors to keep the Java platform relevant.
d) The Java ecosystem has grown because of the diverse range of vendors. It's easy to make an argument that JavaEE only survived the .NET onslaught back in ~2002-2005 because of the high-quality and free implementations from Apache. The current biggest growth market for Java is in non-traditional areas (eg, Google's product: AppEngine/J, GWT and especially Android). Oracle should work with these vendors to keep the Java platform relevant.