"Old School" is a term that can have unfortunate connotations. Some would infer from the word "old" that something would be outdated or obsolete. I think that that would be very unfortunate. I prefer to think of "old school" as "fundamental" and not apply it to any time period. To me it is about the basics on which you build. A drummer can be progressive, and yet be founded on old school fundamentals.
Cases in point would be the Moeller phenomenon, or the re-discovery of the playing of Frank Arsenault. Many have considered. Moeller as being very dated, "Old School" if you will. Yet some of the best drummers of this age still faithfully study and apply the principles of Moeller, and would themselves be considered progressive, such as Steve Gadd. Moeller books as still selling due to a more recent appreciation for a firm foundation to stand on.
Frank Arsenault's great recordings of the fundamental rudiments, and his recordings of the classic solos are now available on CD, and there is not a drumline drummer ANYWHERE who cannot be benefited buy a study of them.
I prefer to think of "old school" as nothing more than the time tested and tried methods which form a sure foundation for success, and a platform for modern innovation. Old is not bad, it is fundamental, and after all, "all things old are new again." I hope we never subscribe to the idea that old is bad, and new is good. We risk loosing a great heritage, and that which anchors us in the realm of music, and not fanatic crashing.