Satellites have a useful life span of 20-25 years. Some last longer, but the limitations are more around the amount of propellant that can be carried to keep the satellite on station, and to move it to new positions.
There's a number of satellite "constellations" at geostationary positions, giving global coverage. Theoretically, you can cover more than 90% of the earth's surface from 3 satellites, but in reality, there's many more, currently providing more than 5000 channels to various parts of the world.
Once a geostationary satellite has completed its mission, it is pushed several thousand Kilometres higher into a Junk or Graving orbit using the last of its propellant. There's literally hundreds of them up there in orbits that won't degrade until long after humans have disappeared from the earth.
Satellites providing Internet services are launched into low earth orbit - similar to the International Space Station, hence why you need many more of them to cover the earth. This reduces the power needed to communicate with them, although earlier fixed satellite Internet services using geostationary satellites could use 15w ground stations with 1.2m dishes. These satellites tend to be much smaller and are de-orbited at the end of their mission, usually over the Pacific, well away from shipping lanes.
Compare the lease cost of a few transponders on a satellite to the infrastructure required for Internet based playout services and I doubt there's much in it currently. There's the issue of latency with streaming, as it's not as simple as just allowing lots of connections to the same live stream, leading to latency of about 10-90 seconds, depending upon the service provider. Not an issue for most content, but any sporting events with betting allowed up to the end of the contest need very low latency to prevent cheating and abuse. News and current affairs also benefit from live playout, but I think the concept of fixed "channels" is coming to an end, and we will simply pick genres and programme types to watch, and the technology will create customised playlists based upon our preferences.
I do think the era of large ground based TV transmission is almost over, but maybe not for 10 years or so. Radio is more likely to continue for longer, as there's too much reliance on simple radio receivers, and public pressure to retain it will remain strong.