Will the OM-D sensor degrade over time?

A legitimate question, perhaps. The answer is certain, given a long-enough span of time: Yes.

But, consider this: All we have are moments to live. We degrade over time as well. We use cameras, tools, to try to preserve some moments. The images aren't immune to time either.

Which is not to say that photography is futile. Not at all.

As time and attention are finite resources, consider whether the longevity of a sensor is really a matter you wish to spend yours on?