I believe we'll all find that our leaders in DC use the word "voluntary" in just the same way that the IRS does in labeling our participation in the income tax as "voluntary".
I predict that this vision for "voluntarism" will ultimately prove to be one for mandatory participation, with provisions that allow a citizen to "buy their way out". Ultimately it is simply another tax.
Don't believe me, though, any predictions I make are based only on observance of past events and a gut feel for human nature.