Dumb idea, in addition to letting in weak teams that over-achieve in garbage time during the second half it can't be scheduled fairly. Getting rid of inter league play means returning to an unbalanced division of teams. What if DC has an unusual number of rain outs in April and May, they'd have to be rescheduled for June or would the make up games in the second half count towards the standings for the first half? How are they going to have all 30 teams have played exactly 81 games by the All Star Break? They'd have to do 80 and 82 games so that each team has an equal number of home games. Plus this removes incentive for teams to play their way into the playoffs in September if they've already clinched.
The best idea for improving the baseball schedule is to revamp the wildcard, division, and LCS rounds of the playoffs. There should be six division winners and six wild card teams, the six teams in each league would each play 15 games in 19 days (five 3 game series), with home field advantage awarded based on regular season standings. This adds tons of profits to MLB due to all of the additional post season games, forces teams to use at least four starters in the playoffs, and eliminates the one and done wildcards that suck for teams that spent six months qualifying for the playoffs. The two teams with the best records after 15 games meet in the World Series.