I have been thinking of how my current setup of T3i/18-155 kit lens/70-300 US ISM (non L) would evolve over time. With time and experience, I could see myself with a something like a 10-22, 15-85, 70-300 L, or something like that. Maybe switch out the T3i for a more advanced crop body down the road..
But with the coming of the 6D, I am wondering if we are approaching a crossroads as FF bodies creep down into the "prosumer" or even "consumer" range. Given that EF-S glass does not work on FF bodies to my knowledge, does this mean that investing in a lot of EF-S lenses may require some careful thinking?
There are two possible ways this would play out in my mind. If a crop body represents the end of the road in my photographic evolution, then there are no issues, assuming that this is viable long term (I am thinking of an analogy with film cameras which are essentially obsolete for the casual photographer, I think). However, if indeed crop bodies go the way of the film camera as FF bodies get more affordable and crowd downwards, would one be stuck with a buch of EF-S glass that essentially would need t be replaced? Or at least, if a person is about to buy EF-S glass, should he carefully think about this given the 6D? As a casual amateur, it seems unlikely that I would ever invest in a top-of-the-line FF camera.
In other words, is the 6D the harbinger of the demise of the crop body? For someone who has not invested in good glass yet (like me), would they be better off investing in glass that is compatible with FF cameras? Am I just talking nonsense? 
). My question was only based on the speculation of whether the APS-C camera is an endangered species. I can easily see me on a 7D for the next 10 years, so I am leaning towards just getting the lenses I need now and focusing, pardon the pun, on learning to use them properly.
