surly bikes have the advantage of perceived exclusivity(few shops refer to themselves as a "surly dealer) coupled with ready availability (any shop with a qbp account can get 'em). So, they seem boutique, but everyone seems to be aware of them. Non-cycling friends of mine (who tend to have other cycling friends, beyond yours-truly) have all heard of Surly, and generally feel that i've got something special in my lht. Strangers in suburban NJ tell me on the street and in cafes that my bike is "really nice". It also helps that surlies tend to be built from the frame-up, and that there are no "junior models" among the completes. RB1s, XO1s, and MBzips are worth a mint; the lesser models, not so much. The surly completes are not offered in tiers. Perhaps future collectors will discuss the decisions made by the original and subsequent owners in terms of the build. Ppl will be able to upgrade their turn-of-the-century surly bikes with whatever period-correct components they'd like, b/c there is/was no original equipment to worry about with, say, an instigator.
But, although i own and enjoy my surly, i kinda feel like the "marque" doesn't deserve any future classic status. The bridgestones that are collectible (ie, grant's bikes) are at once practical and (arguably) innovative for their time. Many surlies are practical, and some are innovative, but i can't think of a single surly model that is both, at once.
My guess as to which current bikes will be future collectibles? In the usa, i'd say Gunnars and Ventanas. The last of the domestically-produced bikes that are somewhat affordable, with a modicum of dealer support. Obviously, most truly expensive bikes will have potential for collectibility, so i'm concentrating on frames that can be had for <$1G. I'm not a big fan of either company, although i've considered a rockhound. And, neither is particularly innovative. Still, i think the potential is there.
-rob