Yeah, but if you qualify for Medicaid now based on your current income then you should enroll, as it's expansion (increasing the income levels) was part of the ACA too, assuming you're in a sane state. At the point in which your income goes above the Medicaid cut-off you should still be eligible for some subsidies up to a certain point. After that, depending on what state you're in your monthly premiums on an exchange plan will be very very reasonable. Anywhere from $50 - $300 for Silver plans, again based on your state, and if you qualify for a subsidy then obviously that's reduced.
Don't quite understand why you think it doesn't work for entreprenuers. I myself left a cushy job around 10 months ago to do a new start-up and I signed up on the NY exchanges nicely, with a monthly outlay of a very reasonable $150.