More competition in healthcare could be a good thing--many say it's bloated and overpriced. The risk is that poor people get basic care while rich people get full care, widening health disparities.
It's unclear what the new healthcare economics will look like. Currently, minor procedures are profit centers for doctor's offices and hospitals. They subsidize complicated patients (often elderly with multiple chronic diseases like diabetes or COPD) who are riskier and take more time to treat. If CVS is taking that money, then hospitals may need to do some cost-cutting.