Hey, I just found out about this and definitely want to share with everyone else here that cares about their trans-atlantic ping times, or even across West-East Europe!
These guys are basically promising a 1 ms latency for every 100 km between you and the other participant, on their network. Take for example the round-trip time between Eastern Europe and San Franscisco: right now, average is 300 ms. With Subspace, that would be ~10000 km / 100 = 100 ms! A 3x improvement!
So while 100 ms is still a bit slow to allow Valve to host a purely online major global DotA event, it paves the way for a much better service for us, the players – for us, 100 ms is more than enough, allowing us to queue globally and play quality games with any of our friends! All that needs to happen is for Valve to sign up with them and connect DotA players through the dedicated network, for a vastly improved service.
They are still building the whole thing, but it seems to be going pretty fast, so maybe in 1-2 years, the network could be fully production-ready so we can benefit from it. If you're interested in a 40-minute talk about it, see
Source: https://www.reddit.com/r/DotA2/comments/pkg700/subspace_is_building_a_premium_global_private/