I put the same question to Tanner Bell, of Smart Fantasy Baseball. Here is his response:
"I will admit that league-wide projections and trends are not really my area of expertise, but I do think I’d project the strikeout rate to continue to increase. In a normal environment, it would be silly to expect a stat to continue to increase indefinitely. You would expect regression, like you mentioned.
But this isn’t a stable or normal environment. We continue to see trends in MLB that suggest teams want more power/home runs and they’re willing to accept additional strikeouts.
I think with the added priority put on batted ball data, players will continue to strive for more fly balls, more power, and more strike outs. I see no signs that teams want to slow these down. I see no sign they think those have gone too far.
On the other side of the coin, we also have better metrics and data about pitching and how to strike more batters out. More attention being paid to pitch speed, pitch mix, etc, I think pitchers are better equipped to strike guys out. Couple that with the decrease in starting pitcher innings and an increase in super talented and strike out heavy relief pitchers, I see the strike out raise going up yet again."