Dream on.  No you can't just walk in and get low cost health care at a community health center or low cost mental health care. It's hard enough for people to qualify for Medicaid. No medicare until age 65 or if you are on SSD & possibly  SSI (limited income and resources who are disabled, blind, or age 65 or older. Blind or disabled children may also get SSI). I double-dare you to qualify for SSI and/or SSD unless you're dead. Knew a guy who was in a coma and social security didn't want to determine him disabled. In a coma. Deemed not disabled. 
Many insurance plans thru insurers have high deductibles, just as they did before the ACA, and/or provide limited coverage. 
If the ACA goes away so will adequate Medicaid. Who know what'll happen to Medicare. It's not cheap for those on a small fixed income.