It's not really news, though, is it? There hasn't been any official notice of a serious/terminal illness - she's just a (from tomorrow) 96yo woman whose health is in line with the health to be expected of a 96yo woman - better than average, in fact.
Even if we had been informed of a terminal diagnosis, what can we really do about it anyway? The Queen would die, the new King is in place to take over immediately: what reaction are we meant to have, other than maybe butter some scones and put out black bunting?
The only 'news' that we really have is that the Queen is a very old lady and unlikely to be with us for decades to come. I'm sure your DS is already well aware of that, not that he can do anything much with that knowledge anyway.
I do find that some elderly people start to feel a bit left behind by progress, technological advances and changes, as well as what they can no longer do that younger people still can. Plenty graciously accept their stage of life and what it means - and are usually very happy indeed to see their grandchildren enjoying the prime of their lives, with the natural acceptance that they themselves have already had the majority of their own.
Others (especially some men) find themselves unable to do this, though, and will try to magnify the things that interest them or that they understand as of immense universal importance, whilst denying that anything alien to them has any importance at all, and will trumpet the world that they know more about than the youngsters as if it's all that really matters.