Copy right is 70 years from the death of the author - or 70 years from the publication date of posthumously published works. All unpublished works remain in perpetual copyright until published - e.g. any letters you might have - and the intellectual rights over them rests with the estate of whoever wrote the letters. Some works are in perpetual copyright - e.g. Peter Pan. International boundaries must respect the limits of other nations as far as I know - Spain has a limit of 80 years.
However the Tolkien Estate has also registered as Trade Marks a lot of the necessary words you'd have to use in order to write a fan-fic and have it published. They exist as long as those words/phrases are in use. Note that copyright expiry allows you to publish cheap One Quid copies of novels, not to use the intellectual property to make new stories - and the existence of extensive Trade Marks will reinforce that. Put that together with the Trust and you ahve an exceedingly complex situation.
So don't hold yer breath...
...or you'll go blue...
As I say the Estate are exceedingly accommodating by allowing such extensive fan-fic as it is, as they are quite within their rights to prevent us all from using certain words and types of character, no doubt. It's a pleasant situation as it is, why change it? It smacks of people being vultures to me, when they could go off and use such prodigious talents to publish something original in order to make a few bob if it's so important. Fan-fic as it is stands as a touching (in many ways, not
all of them 'touching' in a good way
) tribute by fans to their favourite writer.