Subject to ratification by the 30 MLB teams, there are going to be a bunch of rule changes instituted this year and next.
Trade Deadline: The August waiver trade period will be eliminated. The July 31 Trade Deadline will be the only deadline. Players may still be placed and claimed on outright waivers after July 31, but trades will no longer be permitted after that date.
Three-batter minimum for pitchers: Rule 5.10(g) will be amended to require that starting pitchers and relief pitchers must pitch to either a minimum of three batters or to the end of a half-inning, with exceptions for incapacitating injury or illness. This will effectively end the so-called “LOOGY” (left-handed one-out guy) and other specialist roles in which pitchers are brought in for one very specific matchup.
The trade deadline change will take place this year while the three-batter minimum will go into effect in 2020 if/when the clubs ratify the deal.
Source: Anthony Castrovince, MLB.com