I bought my road bike in July. It won't need to be upgraded for a while, but...
When it comes time to upgrade, it will probably be directly to a second road bike. Why? While Bluewing (my teal Giant) fits me fine (or, as far as I can tell, it does...) and I'm okay with Sora components at the moment, there will probably come a time when I want something lighter and with a better "shift-feel." (I'm making up words again; there's probably a technical term somewhere.) It makes the most sense for me to upgrade to 105, maybe Ultegra. If I upgraded the bike (wheels, components) to the higher level that Giant makes using the same frame (Avail 1), it would actually cost the same or only slightly more to buy a new bike. There's a Cannondale I've got my eye on...