I can't see any of the owners wanting this. They're already complaining about the value of current contracts as it is, no salary cap would drive up the market value for all of the players across the board. Mega Stars would be making 150M+ (from big market teams obviously) and then that just shifts the scale up for everyone else. Owners would be getting seriously F'd in the A.
Their stance is to slash salaries, no cap allows absurd deals like the one A-rod got. Then whenever someone has a good season in their contact year they can hit the jackpot and get $96M over 6 years like Beltre, as apposed to the 5 years $60M that we wanna sign Chandler to.