Western plans for Syria don't in any way anticipate the end of the civil war with the downfall of the regime. On the contrary, they aim at intensifying the civil war between the different armed groups after the fall of the regime. Look at this line by David Ignatius: "The United States should step up its training and supply of moderate Syrian rebels — less to topple Assad than to provide a counterweight to jihadists in the opposition and help stabilize a future Syria."