I think will they be classic is a different question from will they be collectible. Certainly there will be those who will see today's carbon uber bikes as collectible, most everything becomes collectible at some point. Being classic is really defined by how the bikes will be perceived by the people of the time. We percieve lugged steel as a superior construction method for various reasons. But will people 20-25 years from now perceive a current carbon frame as superior to their micromesh carboceramic (making that up) frame? I don't think so. Now that frames are composite I think earlier composites will be looked down upon much more than steel is "frowned upon" by the majority of the masses now.
The move from steel to alumimum to composite is such a quantum change. The move from carbon to micromesh carboceramic is less of a quantum change.
Did I make sense?