I never marched in a corps, but I was in a 'highly competitive' marching band back when BOA was MBA. Same experience? Not even close, I'm sure... as judged by friends of mine who did march corps.
The 'we/they(age-related)' argument is sort of nonsensical, because everyone on this board wants DCI (in some form) to continue. In recent years, I enjoyed far fewer shows than I have in the past. That said, there are still enough shows each year that allow me to enjoy the activity. When that is no longer the case, I'll move on to another activity to spend time/money on.
Is it drum corps? At the moment, I think it is, with a few exceptions. Would I like to see symmetrical drill and 2-valve g bugles? Not really. I miss the power of those hornlines, but corps are figuring out how to play their newer instruments as (or much more) effectively.
It should be interesting to see what DCI becomes in the next five years. Until then, I'll continue buying merchandise from those corps who appeal to my particular taste. Come to think of it, that is the way it has always been.
The term 'dinosaur' is often thrown around, and I don't think it means much. Across ages, people have different ideas of what drum corps should be. We'll see where it goes.