The ability to detect isHuman just seems to be on chopping block as far as I can tell. There is little to no barrier remaining today to prevent people from leveraging AI to get around this entire problem. There's a few outlier solutions that work for now, but AI does two things really well given time: solving classification and regression problems.
What can still be done is maintaining short lived replication logs and pattern analysis in this space. There is no reason that a player's actions can't be logged, analyzed, and responded to. It doesn't even need to be real time, it can just be latent. The server doesn't need to rely on reported timestamps for the analysis part, because the server can use it's own timestamping upon arrival to at least see how far apart the order of operations occur.
I know it's not an easy problem space to be in, I don't envy it, but I can't agree with the sentiment that it's impossible knowing how these systems are already designed in larger engines.