The Wall Street Journal has just published an article suggesting that there are another seven countries that might be added to those already 'blacklisted' for ESTA purposes - Syria, North Korea, Somalia, Yemen, Libya, Iran (and Venezuela for political officials).
From the article: "The new restrictions would apply to travelers and immigrants from Belarus, Eritrea, Kyrgyzstan, Myanmar, Nigeria, Sudan and Tanzania. The countries wouldn’t necessarily face blanket bans on travel to the U.S., but could have restrictions placed on specific types of visas, such as business or visitor visas, administration officials said."
Whether this means that, as a non-American, if you've visited any of these new countries, an ESTA would not be issued and you'd have to apply for a B1/B2 visa remains to be seen.