I would say that yes over time their senses would diminish.
Walking Dead wikia
The dead corpse of anyone that dies for any reason will reanimate as a
zombie, unless the brain of the individual is badly damaged or
destroyed. When a person dies, the infection they carry reactivates
critical areas of the brain that support necessary vital systems,
resulting in reanimation. Because only a portion of the brain is
reactivated, the reanimated person retains only a physical resemblance
to their former self.
Because they are rotting, they are destroying some of there nerves that help with the senses, so while their senses would be better than ours, unless they evolve and stop rotting they will loose their senses or part of them.
A zombie "lifetime" varies, though it is know that a human will likely
outlive a zombie through the course of many years/decades
Also, their senses are based on a lot more than nerves.
Zombies have the ability to detect scents and differentiate between
the living and the dead, and prefer to feed on living flesh. Covering
one's self in the scent of decay can act as a camouflage. They can
also use sight to distinguish living from the dead, although they seem
to have poor eyesight as their irises fade and decay, but they make up
for it in very heightened senses of strong hearing and smell.
According to Wikipedia and some medical textbooks pain is considered or 1/2 way considered a sense. And zombies can't feel pain.
Walking Dead Wikia
Zombies feel no pain.
So while I see no hard evidence I think that it is hinted at through deduction. Theirs brains are flesh and their flesh rots, so even if the body is halfway okay over time sense should diminish.
And if you consider this canon, from the wikia:
As zombies decay, however, their muscles, and consequently their
entire body, becomes slowly, but surely, weaker.
And I would say that it would take quite some time.
A reanimated body responds to stimuli such as light, scent, and loud
noises. Oddly, even if the head was separated from the body, as long
as the brain was intact, the head would still attempt to eat anything
within reach.
Unstimulated, zombies stand still or shuffle around rather slowly.
When in this state they are referred to as "lurkers," as they can
quickly activate and attack and kill.