Since MLB is proposing new rules, here are my suggestions --
1: stealing first base -- any time the ball is pitched and has passed home plate, and first base is not occupied (unless there are two outs already on the batting team), the batter may attempt to steal first base. Once the batter passes the cutout circle around home plate, the batter is attempting to steal first and may be put out by a tag or a throw to first (or any other base to which a runner is forced to attempt in the case of two outs on the batting team). If he successfully reaches first without being put out, he will have stolen first base.
2: infield fly rule -- there is no infield fly rule. "If it hurts when you do that, then don't do that." -- Doctor HeeHaw.
3: infield shift -- go ahead and take your chances.
4: opener pitchers -- if the starting pitcher cannot complete three innings, the other team will be awarded a base runner for every out short of nine that he has completed. This will appear on the boxscore as a series of intentional walks to the next batters in the batting order from the time the starting pitcher leaves the game. Note -- if in the opinions of the umpires, the starting pitcher must leave the game through no fault of his own (such as, but not limited to, injury or deliberate action by the other team), the penalty base runners will not be awarded.
5: relief pitchers -- any player on a team's roster may become a relief pitcher no matter what the score (do not ignore 4: above).
6: homer runs -- once per game, the batting team may claim a home run for any fair hit ball that would have been a home run in their home ballpark. Note: this rule does not apply to games played in a neutral location that is neither team's home ballpark.