What year would red foxes go extinct?

The Red Fox exists in abundance in every country in the northern hemisphere.  In North America there are at least ten times more Red Fox now than existed when the Pilgrims landed in 1620.  The Red Fox will be extinct on the day all life on Earth is destroyed.

It's hard to imagine the way in which they're going to go extinct due to how widespread their habitat is. 

A new disease could possibly do it but with their wide range i doubt it. 

Invasive species won't do it because i am pretty certain no invasive species today could do it, red foxes have carved their niche in todays most competitive terrestrial biomes. 

A meteorite could do it but these are very rare so i doubt they will make it to that day, they will be gone before the next big one. 

I can't tell you the year but i'd imagine as global warming continues, carnivorans or foxes from warmer climates will proliferate taking their habitat. As long as people are around i am sure we will conserve them. 

Conservation and zoos would keep that from ever hapening.

The reason for declining numbers is mans encroachment into their habitat.

Being bred in captivity, their domesticated numbers will thrive.

It's unlikely that they will go extinct before we do.  The main cause would be a disease transferred from dogs... with the implication that dogs would be going extinct too.

...But you never know.  "A large meteor can spoil your whole clade," said the dinosaurs.

"I want to pretend this imaginary thing happens, even though it's not going to. Now I DEMAND you tell me exactly how and when and why it happened!!!!"

How the hell are we supposed to answer that? I'll go with an invasion of aliens from Venus.

red foxes are very widespread and are not even endangered.