Over how long a period of time did you notice it? Was it all at once, days or weeks?
It might be trouble with a processing board, not optical/lamp related.
I never heard of any of these getting 'dark' except over thousands of hours of use.
Abundant OTA television is what makes this country different from all others. Lets keep it this way. If you like Wi-Fi so much, OTA fits right in. After all, it is wireless.