US annexation of Mexican territory was not in the cards anytime in the 20th Century. Only if we saw a complete and permanent collapse of the Mexican state (as a result of the Mexican Revolution/Civil War) might the US decide annexation of certain territories to be desirable versus the new status quo of feuding warlords.
However, I don't think Veracruz, despite the importance of the port and oilfields, would be one of those areas. It's not contiguous to the US and would result in ongoing security issues. It would be more likely annexation of areas in the north, particularly in the northwest such as Baja and Sonora and even Chihuahua. Those areas are sparsely populated (making it easier to assimilate), have lots of local US investment in mining and ranching, serves as a buffer to the current American border and population, and even has some substantial pro-US groups there (such as the Mormon colonies and the economic ties).
However, we'd need to see a very different revolution that sees a complete collapse of the state (as opposed to some group seizing control of it). It might happen given the many diverse interests who would fight each other for the next 10-20 years that the revolution unleashed, but it is very unlikely.