What was the effect of AlphaGo on Go?
I've read a couple of articles discussing the impact of AI on professional Go, the second one being a reply to the first one:

Impact of Go AI on the professional Go world
Impact of Go AI on the professional Go world, Response

Some quotes from the first article:

The second important change I see is the professional players’ race to
learn from AI. (...) it’s a unanimous belief that you need to play like an AI to
win, and every serious player has an AI set up at home. Now, there are
both up and down sides to this. The upside is that we sometimes see a
player who was somewhat past his prime suddenly climb back to the top,
having trained with AI more intensely. There are a growing number of
young and new pros who demonstrate surprising strength.


(...) however, pro players have lost the passion or motivation to develop
their own styles. Before AI, most strong players had distinctive
flavors of play and oftentimes this style was the reason why some Go
fans rooted for one player over the other. Today, everyone is trying
to imitate the AI style, and the pros judge each other only by who is
better at playing like the AI.

The second article refutes the gloomy side of these observations:

While I agree that ai-inspired moves are now increasingly common among
top players, I predict that the situation is a bit more like if
Ancient Greek mathematicians were given a graphing calculator: of
course they will first lose themselves in playing around with the new
toy, but eventually they will get used to the new possibilities and
life returns to a slightly more normal state. For top professionals,
it is valuable to be aware of the newest developments (or ‘meta’) so
that one can on the one hand avoid larger mistakes, and on the other
save valuable time during tournament games. Besides top games, I
suspect the ai has actually made more styles of playing possible.

PS: Bold added for emphasis