How do they define "PC" that theirs is the "world's first"? If I remember correctly people have used RISC-V systems for desktop stuff before.
Note that the article doesn't say whether this "PC" will be an actual product that SiFive sells.
Well, the official press release is titled "SiFive To Introduce New RISC-V Processor Architecture and RISC-V PC at Linley Fall Virtual Processor Conference", so that does suggest some sort of PC-like product.