Books, are exactly that. Books. I separate books from support the same way WotC does. According to WotC, the economics that support the decision to eliminate the magazines and go 100% DI are not valid when applied to core books. The 2 are distinct in my eyes and WotC's. Dragon and Dungeon supplied support in various ways for the D&D community. The DI is designed to replace that support and hopefully enhance it. You might not consider D&D players who do not have access to computers or the net to be marginalized by the reality of the DI, but I do.
Of course this is all subjective opinion.