Yeah would love to have a RISC-V board with similar performance as a Pi and that isn't as expensive as the hifive unleashed. Haven't found anything yet.
The likely source will be lowrisc.org. Several folks that were involved with the Rpi are on the project.
"We will produce a SoC design to populate a low-cost community development board and to act as an ideal starting point for derivative open-source and commercial designs." - https://www.lowrisc.org/docs/untether-v0.2/
I wouldn't hold your breath (although I wish them luck). There are however a bunch of low cost high performance RV64 chips coming this year and next from China that will change things dramatically. (I'm a Fedora/RISC-V maintainer, and I'm in Beijing today and tomorrow talking to RISC-V people. It's 23:57 here, got to go to bed :-/ )
As is always the way with these things, unfortunately I'm under an NDA until the products are released. However I can tell you the rather obvious thing: We're helping them to understand how to get changes they need integrated into upstream communities (kernel, GCC, binutils, uboot in particular) so that their hardware will boot without patching when or soon after it is released.
"We will produce a SoC design to populate a low-cost community development board and to act as an ideal starting point for derivative open-source and commercial designs." - https://www.lowrisc.org/docs/untether-v0.2/