The Republican Senators couldn't overturn Obamacare because it was a great system (it's not--government spending is rising much faster than originally projected while revenues are falling short); the Senators didn't want to be blamed at the ballot box for the pain of the transition---just as the Democrats were blamed from 2010 to 2016.
One doesn't go changing a system where hundreds of billions of dollars are spent without some good, innocent people being harmed. In 2017 we would have been treated to stories about people who lost due to Obamacare's repeal. The difference was that in 2013 we didn't hear about people who lost their doctor and/or their insurance plan because of Obamacare. Unfair, but that's the media landscape.The next order of business is to decide how much to fund the health care system that so many Republicans disagree with. Frankly, I'd start with the 2009 CBO projections that were used to pass the bill, perhaps adding 5-10% for overages.
Opponents at the time said that Obamacare advocates were lowballing the costs in a classic get-it-passed-so-we're-stuck-with-it move. Let's see who was right.