There are many children who never saw a gurukula, but who are still strong in their desire to be Krishna concious. Conversely, there are many children who were raised in gurukula, but their experiences were such that they rejected Krishna conciousness as they grew older. Of course, the gurukulas remaining today have learned a lot from the mistakes of the past. But one thing that has also been learned is that it is the duty of the parents to teach Krishna conciousness to their children by their own example. In the long run, that will bear the most positive impact upon their children, whether they grow up in gurukulas or in slaughtehouse schools.
Collected Letters to Friends and disciples Vol 4, Pg 95, 2nd paragraph.