I forget who it was when asked what R’s had to replace Ebolacare said “If you put out a fire, what do you replace it with?” Thomas Sowell, I think.
Seriously, if things are worse now than before passage, then it’s self-evident that standalone repeal would be an improvement.
Now, would there still be room for reform? Sure, but it has to do with damage done by previous rounds of government “help”, not with the minute amount of freedom that survived in the healthcare market pre-ACA.
If the court strikes down Obamacare in June of 2020 then 5 months before the election the pre-existing coverage requirement, the elimination of caps on coverage requirement, and the coverage of dependents up to age 26 requirement all are struck down as well. While Obamacare as a whole may not be overly popular, those three aspects of it are the exception. So five months before the election the Republicans will have to explain why they eliminated those three popular features and the Democrats will have an issue that they can run against. And if McConnell really thinks that Congress would "act quickly, on a bipartisan basis" to fix it then he really is a colossal idiot.