Not Fanfic But

I cannot write fan fiction but can speculate about obscure potential sequels to existing texts:

What becomes of country roads in Cumbria after the fall of Poul Anderson's Terran Empire (see here)?

Might SM Stirling's Rangers and Tolkien's Elves meet in Anderson's Old Phoenix Inn between the universes (see here)?

What will become of Lancaster in James Blish's Okie History (see here)? (I do not think that it will go Okie.)

Might Ys have gone Okie if, instead of being inundated, it had survived into the Okie future history (see here)?

Might the Time Traveller, the Doctor and the Time Patrol interact (see here)?

Examples could be multiplied but I think that these five are sufficiently suggestive.