Chromebooks use Coreboot, and they regularly top the lists of most popular laptops on Amazon. The firmware/binary blog thing isn't as much of an issue as you might think, since the basic idea of Coreboot is to do the minimum possible to boot the OS rather than replace all the random BIOS functions and crud built up over the years.
Replicant is likely a response to Cyanogen giving up, and an attempt to find some way around the binary blob hell that is smartphone chipsets. Well, these days Android runs on a lot more than just phones, and things like tablets tend to have more transparent hardware for their radios so it's far from an impossible goal.
Personal assistants could easily use your own personal server. The speech recognition might not be quite as good, but of course you can just type stuff. In any case, being able to look up results on your choice of search engine or Wikipedia, and being able to interpret simple commands like "set a reminder for next Tuesday at 7 PM" hardly requires billions of dollars of hardware. There are some useful Google Now features I don't use for privacy reasons, like traffic info cards, which could easily be replaced by free software even if I have to explicitly tell it my route home from work rather than it using machine learning to figure it out for me.