I suspect that's because it looks like the republicans will have to keep it going for existing participants while they figure what to replace it with, but if you are not in, you are definitely out.
It's a difficult thing to replace, because Obamacare gives coverage to many people with existing conditions (ie the folks who need healthcare) and the insurance marketplace considers such people bad risks (ie insurers don't want to cover sick people if they can avoid it).
The trouble is, people with existing conditions become a political issue to the party which withdraws coverage. Even if the insurees die off because they can't afford healthcare, their family members might just remember who was responsible for an act of such malice.
This is the epicentre of all that is wrong in the US. The free market doesn't solve issues like this, except via exclusion. There are reasonable alternatives to Obamacare, but none of them are market-driven. That is, unless you are content to have sick people lose everything.
No one wants to be sick. If you have a normal level of human compassion, you can't just repeal a programme which supports sick people in a way that is just about affordable. That is, unless you have a viable alternative.
Unfortunately, Republicans often seem to lack compassion in their politics, which is why you often think you are talking to a sociopath in a conversation with them about healthcare. Their principles matter more to them than people dying or being forced into bankruptcy. Whereas these things become very obvious when you are affected by them.
So my guess is we will see a repeal which pretends to be supportive of people that are covered, but which actually leaves them screwed. Can you say Trump shop-for-your-doc healthcare vouchers?