With the deficit in the US and the bill for social Security and Medicaid coming due for the "baby boomer" generation, I believe this is a real threat.

I pay my tax to the US, but I consider Switzerland my home. I am not an activist but I think an issue is that Americans Abroad do not have representation. We are not united and there is not a strong voice for issues that impact us. Senator Chuck Grassley a key member of taxation committee and Senate finance committee believes the Foreign earned income exclusion should be eliminated. This is a strong concern because he has slipped in tax changes before that have impacted Americans Abroad.

"Since 1976, Rep Chuck Grassley, Senate Finance committee has repeatedly introduced measures that increase the level of double taxation on American citizens living abroad, including retroactive tax hikes. Grassley was eventually able to attach an amendment to a unrelated piece of legislation that went into effect in 2006, which increased taxes on Americans abroad by targeting housing and living incentives paid by foreign employers and held them accountable for federal taxes, even though they did not currently reside in the United States."

That 2006 tax change that increased taxes on Americans abroad was slipped into another non tax related bill at the last minuted by representative Chuck Grassley. It was not even debated and almost no one in congress knew it was there. Grassley believes that American's Abroad are a major source of additional tax revenue and is a supporter for elimination of foreign earned income exclusion.
http://www.nytimes.com/2006/05/30/business/30tax.html