The Freedom E310 chip in the HiFive1 board is shipping today and is already competitive with embedded ARM: https://www.crowdsupply.com/sifive/hifive1/#comparisons. It's comically faster (i.e., 100x) than the AVR chip in the Arduino Uno board, but the similar form factor makes it cheap & easy for early adopters to play around with.
I'd bet that within five years a good proportion, even the majority, of Amazon & Google servers, will be running on RISC V chips.