In some sense it is more sensational than Lee Sedol beating AlphaGo, because it shows that Go is not yet beaten by AI and that this is only the true start of the battle between humans and AI with respect to Go.
For Go there is no such possible outcome, and deep reading (calculation) will always be in the machine's favor. The architecture of AlphaGo (policy and evaluation networks plus MCTS) is sufficient to recreate and surpass any kind of human-practical strategy. The era of human dominance in Go is simply over.
Of course, current AI programs will never be perfect either, so there may continue to be such adversarial attacks, but they will necessarily become harder to use (and quickly impossible for humans). AI go programs probably have nearly infinite possibility to continue marginally improving against each other, though.
This is an assertion without evidence. Leela Zero uses the architecture of AlphaGo and yet this guy just beat it with a human-practical strategy. I have no doubt that this can be fixed, but exactly how to fix it is not obvious and it may require more compute, and that's interesting.
When learning to play Go, you go to a number of steps, where sometimes you have to unlearn something you learned in a previous step. I am a weak amateur player (around 10k) and I only have a vague idea about aji (taste in Japanese) and no idea what good aji and bad aji is. I even don't master life and death. When AIs started to beat professional Go players, it seemed that they had a good understanding of aji, because they created good aji and avoided bad aji. They also played a very balanced game, overseeing the whole board, something that non-professional players often fail to do, and now the adversary strategy reveals that the AIs do not even have a good understanding of life and death and even fall for 'tricks' that I would have been able to counter.
It's the same reason why MOBA AIs get demolished by humans outside of extremely confined circumstances. The training space is much too large for the bots to handle every possible human strategy in games like MOBAs. So what happens is we just find weaknesses where they lacked training with non-standard strategy and we win. Reliably.
Yes, the bots do not lose lane 1 versus 1 with no outside ememy involvement. But once you lift that constraint, we do not lose to the bots as high level players. And it's not like there's only a single exploit, there's many.
In any case, I'm not expert in MOBA AI, but they are much more complicated than go just as go is to chess. So it will take longer, but it's unlikely the long-term outcome will be any different as long as Google etc keep working on it.