I'm pretty sure that eight channel support would require a different socket and motherboards. To me, it would make sense to reuse SP3 (socket used by Epyc) in that case. Since motherboards already exist. The last thing you want is to require a special motherboard. Or socket and chipset intended for next generation Threadrippers. Given that, I wouldn't bet on eight channel support.

AFAIK, Threadrippers actually support up to 1 TB of RAM. Problem is that you're limited to unbuffered modules and the modules necessary to reach such a capacity just don't exist. It has been said that support for registered modules is in the works. The hardware supports it, it just hasn't been validated and support will have to be added into BIOS. That wouldn't give you more channels, but it would allow you to install more memory. It wouldn't surprise me if these "PRO" Threadrippers came with it from the start. With 256 GB modules on the market, you can actually reach 2 TB with just eight of them (which is a common configuration for TRX4 motherboards). Hence, I can imagine a bump to 2 TB.