[jaclaz]

It could well be (for common threaded bulbs) a sort of socket adapter, the base containing the driver and a connector to the actual bulb/led.

The 5V choice might not be the best one, but 12 or 24 V (like commonly led strip are powered) could be fine.

[eternityforest]

USB isn't just 5V, PPS actually lets you request a specific voltage and current, so you wouldn't need driver electronics at all in the actual light, as long as all you want is just regular on/off control, so the light part can be just a bare LED and a communication chip.

A socket adapter might be the best for getting it out there though, you'd need more new electronics but no new construction work. But with a new electrical interface you could cover RGBW too.

I wonder if it would be possible to make the heat sink a separate part too without needing paste or degrading performance, since heatsinks don't wear out