I really want to believe, but I don't think we'll see anything like an M5 chip anytime soon simply because there's so little investment from the bigger players.
There are plenty of multi core designs (that's easy) but they aren't very fast.
In terms of open source XiangShan is the most advanced as far as I know. It's fairly high performance out-of-order.
I don't think there's anything M5-level and probably won't be for a while (it took ARM decades so it's not a failing). I doubt we'll see any serious RISC-V laptops because there probably isn't demand (maybe Chromebooks though?). More likely to see phones and servers because Android is supporting RISC-V, and servers run Linux.
In terms of extensions I think it's pretty much all there. Probably it needs some kind of extension to make x86 emulation fast, like Apple did. The biggest extension I know of that isn't ratified is the P packed SIMD one but I don't know if there's much demand for that outside of DSPs.
That's not gonna beat the M5, but it should be similar or better relative to M1, and a huge performance jump for RISC-V.