Lets say you're writing C. You're going along your merry way and all is well. Except that one day, your code doesn't do what you want it to do. Well, every day. But, this day is special. Today, your code isn't working because of a compiler bug, not because of a bug in your code.

Now, you can either ignore the bug, and hope that it gets fixed. You can work around it. You can use a different C compiler that may not have the bug. Or, you can fix the bug yourself.

Now, lets say instead of C, you're writing Java. Given the situation that Oracle seems to be attempting to make, the first situation won't get you sued, but it will leave you will a bug. The second choice is the best option. But, the bug still needs to be fixed at some point. The third choice might not be possible, because Oracle will have sued everyone else who has a JVM implementation and forced them to stop making an alternative, leaving you with the buggy Oracle/Sun JVM. And the last choice will get you sued.

And, to be frank, three of these four choices suck, and the remaining one isn't a joy to work with either.

OpenJDK is not a dead end - you can extend it and correct any bugs that are a problem to you.