Ancient-Red-Dragon: I'm not buying the premise that there is such a thing as an "undetectable" hack. Rather, I call BS on that, and declare it to be a false premise.
The setup I described is the safest way of going undetected games can't really detect what goes on in the 2nd streaming PC. If you open the hack from the gaming PC, then yes, it's possible for the game to detect that you have the hack on and can autoban.
The simplest solution would be for the game to detect if you have a capture card or streaming programs running. That probably could work for ranked ladder matches, but it also kills the free Twitch and Youtube marketing you get from streamers and their followers.
Another solution would be to collect KPIs on speeds and delays from the highest skilled players and set ceiling detections on the players' speeds and autoban anyone who exceeds frequently. However, it can be circumvented easily as you can see the program by adjusting the milliseconds in delay. Would be easy for cheaters to throw in some RNG seed to 'scramble' the delay so it's not always precisely the same amount. This is why the proposed counter-AI to watch players and monitor their stats is the only effective solution to this unless some CS students / IT people have any other insights to this.
AB2012, Arcadius-8606, and Breja are correct in that going forward, sanctioned tournaments must only be done in-person to avoid all cheating. But if there's no casual audience to buy the game in the first place and practice with others at an eSports level, that kills the game's product life and profitability. That's why this topic is very concerning.
EDIT: Hell, I don't see why this couldn't be tweaked for MOBA games either with a little effort.