The most likely scenario is: The proportion of white-furred rabbits in the population declines.
This is because the increased average temperature and shorter winters may lead to less snow cover, which would reduce the camouflage advantage for white-furred rabbits. As a result, brown-furred rabbits, which are better adapted to the warmer conditions and potentially more visible in the changing landscape, may have a better chance of survival and reproduction, leading to a decline in the proportion of white-furred rabbits in the population.