The Commissioner should declare that if no agreement is reached by August 31st., the current agreement stays in effect for the next 4 years, at which time both owners and union can attempt to negotiate a new contract. This should provide some degree of incentive for both sides to work something out now.
But there will be no work stoppage by either the union or the owners. The game is bigger (and more important) than either the owners or the players, therefore, their inability to agree will not hinder, disrupt, or damage the continuation of the season.
---max