Separate lines for no bags makes plenty of sense, but only in those situations where you have lots of machines/scanners like Denver, Atlanta. Some airports have 1 or 2 in each location and therefore not very practical.

As to separate for elites, not sure this is valid. Just like you do not have parking for elites, drop offs for elites. This is an AIRPORT function, not an airline function. Yes, I know in most cases that the airline "owns" the security at certain terminals or gates.

I am a PM-top level on DL- and would love this, but really have doubts it makes sense to create an "elite class".