Most of the guys being mentioned are not untouchables IMO. In fact, most of the guys in the Reds system are very tradeable. Good, but not the kind of player likely to be dominant.
Chapman is probably untouchable.
After that I don't call anyone untouchable.
If I had to make a list it would be:
Chapman
Yorman Rodriguez
Francisco
Juan Duran
Donnie Joseph -- not untouchable but possibly a Reds mainstay in the near future.
Maybe Mesoraco because of his position.
Even this group is a stretch for untouchable status.
There are other guys who I would hold onto because they haven't had time to show us their ceiling as yet. Like Boxberger, for example.