Personally, I don't consider the Professor's work to be fantasy, in modern usage. I consider it to be the mythological equivalent, if England had it, to the Norse Elder Edda and other similar legendary mythological histories. In his own words, the Professor sought to create an historical mythology 'fairy' story set to England that other Germanic peoples had been known to have. I consider this work of literature to be equivalent to Homer's Iliad, not 'fantasy'. Others have their own opinions.
"No sadder words of tongue or pen are the words: 'Might have been'." -- John Greenleaf Whittier
"Do or do not. There is no try." -- Yoda
On planet Earth, there is a try.
Indeed, in a world and life full of change, the only constant is human nature (A is A, after all :P).
We old vets need to keep in mind those who come after us.