Answer:
One species would be forced to leave.
Step-by-step explanation:
If species A moved to the niche occupied by species B, the competition between the two species would be large enough for one species to be able to completely expel the other species from its niche.
The species that would remain in the niche would be the strongest and best adapted, while the species that proved to be weakest would be forced to leave the niche and look elsewhere.