But you need to buy one that supports LiFi, and LiFi bulbs will probably be more expensive than normal lightbulbs (if they become a thing)

And if you still need WiFi, what's the point of buying LiFi bulbs and setting them up when you can just keep using WiFi? It just doesn't seem to be worth it unless you're in a place with hundreds of WiFi devices (and it still probably won't help a lot).

The LED's need to be able to turn on and off in nano-seconds so you can't just twitch the AC power because the voltage regulator will not respond fast enough (there is enough juice in the capacitors to drive the LED's for a few seconds usually this is why cheap LED light bulbs don't turn off straight away, the more expensive ones have usually have a current shunt that will clear the capacitors to ground when you hit the light switch) and most likely simply die after a few minutes.

So you need to do in-circuit modulation which means a dedicated light bulb.

Well in theory you start building light bulbs that can be effectively turned on and off about about a billion times a second which is not going to happen and even then you'll still need some device that will modulate the light so instead of a dedicated light bulb you'll have a dedicated lamp.

Considering the engineering limitations and the cost involved having normal light bulbs that can connect to your network via either WiFi or well via basically "DSL" via sending a phase modulated signal over the AC wiring in your house similar to how those power plug Ethernet / WiFi extenders work.

https://en.wikipedia.org/wiki/Power-line_communication

Again this is a very kickstarter / TED talk worthy idea that sounds brilliant but it will probably go the way of the GyroJet because it's just so dumb on so many levels.