We see see future fade away. Literally turn to smoke and wisp away.
There are not two time lines or any sort of pollination.
The future rewrote itself.
but the rewrite did not extend into the past before the schism which jostled continuity into a completely new shape.
Which is why the Janeway was... Wait?
Janeway faded too?
But all the knock on secondary effects of her life 2 days in the past still existed?
(The time laws for trek are inconsistent. Just roll with it.)