Is there a limit on how old something needs to be without being able to look at it in a new light?
No, you are right. But is this really looking at it in a new light? Usually links to new articles are very recent ones so I was a little surprised.
But no, I do not think that Ian Huntley is a woman is the answer to your question.
I think that even if the reforms come in, Ian Huntley will not be moved to a women's prison and from the article it seems that he would not request this either. In Scotland there are already rules stating that prisoners should be permitted to express their chosen gender regardless of having a GRC. This does NOT equate to a right to be moved to the prison of your choice. In the vast majority of cases it means you do your 'expressing' in the appropriate prison, which for violent male offenders is a men's prison.