I've seen many changes since I first had my eyes locked on the TV set.
I still miss the days when ABC courted a teenage demographic with TGIF on Friday evenings and courted the male demographic with Monday Night Football.
At the same time, CBS was often looked down upon as the "old peoples' network" due to most of their shows being targeted towards an older demographic outside news, sports or Saturday morning cartoons.
What all TV networks need to do to stay relevant in this day and age, is adapt or die, which is what they did in the 1990s to compete with the Fox Broadcasting Company, when they started to grow at a fast pace (they even gave us The Simpsons as a result of that growth!).
When Fox outbid CBS for the NFL's NFC football package in the early 1990s, many network affiliates formerly aligned with ABC/NBC/CBS aligned with the network as a result, creating a huge "musical chairs" game for many TV stations across the country, when ABC/NBC/CBS abandoned their old VHF channel positions in some market for the inferior UHF channel positions which used to be Fox affiliates.
This was during the analog dark ages when many of the higher UHF positions put many TV stations at a disadvantage with their poor reception in some areas.