Remove the Ai
Split the gold of the player who left between the other remaining same team players
Split the gold per second of the player who left between the remaining same team players
Drop the items of the player who left at crystal
Sounds very reasonable, and technically feasible, too. Hope someone relevant reads this. Also those uneven games don't sound very appealing, TBH. Haven't played online yet, but that's not a very appealing prospect, especially if the intended balancing doesn't work.