[RandomOpinion]

> I guess what I'm saying is that by allowing a device to upgrade in software to more power-efficient designs, you might claw back some of the efficiency lost by using an FPGA when you consider the entire product's lifetime.

That presumes you put in a big enough FPGA/CPU or whatever fifteen(!) years in advance that has enough resources to handle the increased processing requirements for a future protocol (expensive and wasteful and there's no guarantee that you didn't guess wrong and it's still too small/slow) and that your RF signal path was designed well enough to handle the new signal requirements (expensive and wasteful even if you were prescient enough to guess what future requirements were). And that's on top of the fact that inexpensive electronic devices simply aren't built with components rated to last 15 years.

tl;dr software doesn't change the laws of physics