From what I read on site for US Embassy in Santiago, the Chile has been nominated US Visa Waiver program.
http://chile.usembassy.gov/non-immigrant_visas.html
Now, does anyone have idea when this should come into effect that Chilean citizen will no longer need to apply for US visa?
If I have some uncertain/possible travel plans for the end of 2014, should I go ahead and apply for US Visa or should I wait until this program will go into full effect?
You should not rely on US Government to act on this in 2014. It is far more likely that if it will happen in 2014 it will be late in the year and it might be better to apply and get a B visa instead of waiting for VWP to happen.
There is a recommendation by the State Department to the Santiago embassy to:
Informal Recommendation 20: Embassy Santiago should conduct a broad validation study of its B visa applicants in accordance with Bureau of Consular Affairs guidelines and prepare an analysis of the results as part of its new officer training, fraud prevention effort, and visa waiver evaluation process.
And while this document is dated February 2013 given the inertia that US government has in implementation of changes I don't expect this to take less then at least 1 year, so as of right now there is no published effective date on Chile joining the VWP.
NEW INFORMATION
As found on the site of DHS a few minutes ago dated February 28, 2014:
WASHINGTON—Today, Secretary of Homeland Security Jeh Johnson, joined by Deputy Secretary of State for Management and Resources Heather Higginbottom, Chilean Foreign Minister Alfredo Moreno and Chilean Ambassador Felipe Bulnes, announced the designation of Chile into the Visa Waiver Program (VWP)—streamlining travel for thousands of eligible Chilean passport holders, while maintaining strong security standards. Starting May 1, 2014, eligible Chilean passport holders with both an approved Electronic System for Travel Authorization (ESTA) and an e-passport will be able to visit the United States without nonimmigrant visitor visas.
So for the End of 2014 you should now be able to enter US under an ESTA.
