"The Veldt" has several themes from which further sub-themes develop. However, the theme which seems to permeate the most throughout the story is that of man versus machine. However, the story shows that "man" is actually any individual who has weakened as a result of lack of discipline while the "machine" represents any type of high intelligence which overpowers those who become co-dependent to other things for the fulfillment of their responsibilities.
The story's premise is that technology may one day have the power to ease our lives so much that it will even partake in our thinking processes, to the point of enabling our thoughts and emotions to be brought to a palpable reality. As a result, we will be rendered co-dependent on technology, hence neglecting the rights and liberties that assert our individuality.
In the story this is precisely what happens: when George and his wife get their HappyHome, they are excited by the idea of not having to do anything on their own. However, rather than investing their free time back into enriching the family unit, they allow technology to entertain their children, and to spoil them as they please.
As a a result of this, the children get used to the instant gratification brought by their interactive nursery, which brings out the children's fantasies to near-real life. However, as they instinctively want more freedom, they are limited by their parents who are now worried about the effects of the nursery in their children. The children then manifest their frustration by inventing an African veldt, complete with flesh eating lions...the same lions whom are brought to life by the angst of the children and then eat their parents.
Therefore, the carelessness from the parents combined with too much freedom for the children clearly creates a dysfunctional situation. However, the co-dependence on "something other than ourselves" to fix our problems is what ultimately brings on the final tragedy. This is represented allegorically with an interactive veldt. The only time when man and machine will become enemies is when "man" is unable to take control of his environment in the first place. The machine then represents any form of higher intelligence that will inevitably control a feeble and lost individual.