If Rubio runs in 2016, unless he backpedals on amnesty, the conservative base will not support him. He will not be conservative enough. He's not experienced enough, probably, but a Latino candidate such as Ted Cruz might be different as he is anti-amnesty.
A candidate such as Rubio might help with Florida and Northeastern Hispanics, but I don't know how much influence he would have with the Mexican-American electorate found in the Southwest.
I personally do not think changing immigration stance or granting amnesty will have much effect with Latinos and the GOP. It didn't help Bush Sr. after the Reagan amnesty, and the conservative base of the GOP would destroy those who favored it. I agree with Rush Limbaugh...Santa Claus.