When he is king, do you think that William, the current Duke of Cambridge, will restore his mother Diana’s royal status as an HRH?

He has said for years that he will and it will be in his gift to do so therefore he will. EDIT He has said this quite recently.

And you shall be Queen of the May.

IF he said that, that was then. Since Diana is now dead and buried, what's the point????? So no, I doubt this will happen. It doesn't need to.

Styles are not granted posthumously.

When he said that, it was believed that she would still be alive when he became king. It’s of absolutely no value to her now that she’s dead and buried

To a dead person no.

No, it will have little or no meaning. If she were still alive, then I would say yes.

No - he's not an idiot.

It's just protocol to remove the HRH title after a divorce. Diana understood that - and I'm sure that William does as well.

Why at all. The world moves forward.

Dead are left dead and gone.

No