The current medicaid funding to those states that do not expand services under the ACA cannot have their funding reduced as a consequence. This to me is actually pretty big, more so than the "tax" language applied by the SCOTUS, which has it's own problems. ACA may have stayed afloat but it did take on some water.

The states which choose not to raise Medicaid eligibility criteria will not get the extra money allotted to them for such a raise. However, they will still receive all the previous Medicaid money allotted to them under the current criteria.

Am I right to be concerned?

This is a huge hit to the poor that currentlly make too much to qualify for Medicaid, but don't make enough to qualify for the premium subsidies.

I read an estimate today that if all 50 states opt out (which they won't, obviously), ~15 million people will be left with no way to get health coverage.

Add the tax language and it makes it worse.