This is just the first step, it's not gone yet. Republicans must decide how to repeal and replace now. Some (like Rand Paul) want to repeal and replace at the same time (which, if it has to happen, is the responsible thing to do), others want to repeal it now but have a grace period of 2-4 years to come up with a replacement, and some want to repeal it immediately. If they can't agree, then Obamacare may stay.
The scary thing is that if they repeal it, Republicans could literally be like "oh lol we were just joking about replacing it" and never make a replacement