It is not a disaster at all: what it signals to the Left is that President Trump is not the Dictator they have been panicking about: He has so much opposition within his own party that they can stop his Election promises being enacted. So he is no Hitler, he’s just another politician who has to compromise to get something close to what he wants. The American Healthcare Act will eventually be a better bill after being re-worked to deal with the opposing Republican Congressmen’s arguments.
And Trump is no longer scary even to the Left, who are now laughing at him. Pretty hard to go from this amused scorn back to terrified “Resistance”.