While the idea of school readiness is a widely accepted concept, I think readiness for work is more important than readiness for school.
I read a very interesting article recently which suggests that one of the reasons for all the learning failures around the world is the problems created by the movement in the past decades to make learning fun. The problem is learning isn't fun. It is work! Though there may be aspects of work that can be fun, there are also aspects that aren't. But regardless, they just have to be done. It is the same with learning. Thus, it is important to teach a child that work is something that has to be done, and done to the best of one's ability, even if the work is neither interesting or fun.
The article concluded that 'the child whose parents do not succeed in teaching him this, faces a very hard and difficult future'. Maybe a little harsh, but I do concur.
After all, success is 1% inspiration and 99% perspiration. No matter how clever a person is, without the right work ethics and attitude, he still won't get far in life.