Depends on what you mean by "it's going to work"

If by, "it's going to work," you mean to say that a properly implemented ACA with full participation from the states will provide everyone with quality health care regardless of age or income then... no.. it's not going to do that. 

But the part about the states who have actually tried (built their own exchanges, accepted the Medicaid expansion, and so forth) having had greater success getting people enrolled, yeah, that's working well.