I reckon i'm probably safe for a while since i use the PS4. Netflix probably has their reasons based on the amount of subscribers that use these devices and are willing to take the loss. I'm quite certain they look at things like how much it is going to take to recode or whatever they have to do and then multiplied it by the number of people using said devices, then determined it wasn't worth it.
This probably seems obvious :)
RE: Netflix Phasing Out Old Technology Soon