If we had GA's who kept the boarding area clear and moved people away who shouldn't be there, then yes - I agree it would work. It really depends on the staff and customer attitudes. I've seen two-lane boarding work well at SEA and many of the outstations for Alaska Airlines, but they seem to have a different culture which is very "left coast", and customers are less prone to stress inducing behaviors (from my non scientific observations over the years).

Another option is pre-staging pre-boarding customers like NH, but that involves a GA moving out from behind the desk and checking status, moving people in and out of lanes, etc - just not going to happen in the US market.

The chutes are the best option to keep Elite and non-Elite separated and some physical structure to the waiting area that prevents crowding and gate rushing.

When I interned at Eastern and boarded my flights from a relatively confined gate space, I was very strict with my boarding process and told people to sit down until their row was called, and if there was a rush, I just stopped boarding and waited until people went and sat down - they got the message quickly enough. If you think it's stressful for passengers, I can tell you from my own experience, having a mob of people rush the desk the moment I unlocked the door was not comfortable for me either, and I had a choice of either letting it happen and get stressed over it, or take control of the situation and restore some semblance of order to reduce everyones' level of stress.