Toward a two-tier presidential campaign financing system?

This is just a brief follow-up on a previous post on the growing importance of money in politics. Yesterday, former Democratic governor of Iowa and chair of the Democratic Leadership Council, Tom Vilsack, dropped out of the presidential race. Here is why:

"It is money, and only money, that is the reason we are leaving today." (my emphasis)

Is this further proof of the emergence of a two-tier financing system, in which all the top candidates opt out of public financing, while the second-tier candidates are stuck with it? Some push this further and wonder whether this is still a democracy or whether we have fully entered the age of plutocracy. Apparently, Evan Bayh also quit for a lack of money. Can public financing, created after Watergate in 1974, be saved?

"Next week, the Federal Election Commission will rule on a special request made by Sen. Barack Obama (D-IL). It would let him raise money for the general election, and still choose to return it and take public financing if he wins the nomination."