We'll see. ARM architecture is now about 36 years old. I believe RISC V originated about 10 years ago. I think MIPS started about 40 years ago, but I believe it has finally ground to a stop.
The way I see it is that x86 is still around despite ARM, so ARM will still be around despite RISC-V. No reason why all three can't exist.
Not sure why you'd say that - especially if you look at Arm v9 and the fact that the architecture is starting to make inroads into there server market.
RISC-V is open source which is great in some respects but also not helpful in others.
You assume Risc V will be open source when it reaches consumers hands.
Just the design. Firmware and software probably not except for FOSS purist products.