It has been my experience that it takes from two to four years for untreated bees to "die" if they are not treated. Some die in their second year, some have mild resistances and manage to hold out a little longer, depending on when they replace their queens.
Most beginners buy packages, and then opt 'out" on treating because its the easy way out of the information overload, and their bees die. Even experienced beekeepers who buy "resistant" queens and or nucs, find that their hives die when not treated. Taking a queen or nuc from where it has been living without treatment for many years, and hauling it 200 to 2000 miles, and expecting them to survive is a long shot.. I have Survivors from NC, and I have Old Sol survivors. I HOPE I never have to treat them, but it has been my experience that I will eventually do so, to save them.
Taking those survivors, and setting up your own treatment free program puts you a step ahead of buying package bees from California, Hawaii, or somewhere in the south, but you cant expect to stress the bees through travel, and set them up in a different climate with different forage, usually in proximity to hives that are crashing due to mite loads, yours, your neighbors, or even feral hives, and expect them to do as well as they did where they originated. Add in the non resistant drones the replacement queens will be mating with for a wonderful mix of eventual fail..
I believe you can run treatment free. I believe it when you and others tell me they are treatment free. Some keeps have great luck, buy resistant bees and trot on down the no treatment path without a hitch in their giddyup. Maybe its climate, maybe its other resistant bees in the area their queens mate with? Lack of other bees in the area? I dont know how to explain why they can live one place treatment free and not another....
Perhaps it has to do with how many beekeepers could give a rats.... behind about resistant bees.. they have never had resistant bees and dont care if they ever get them, they treat, so any effort I put forth to develop treatment free queens is severely hindered when my queens mate with their drones.
I have had bees that showed fantastic hygienic behavior. They passed the liquid nitrogen test with flying colors. They did well for two years, superseded their queen in year three, and by year four were crashing hard.
That doesnt mean I will quit trying.. I figure every resistant drone I put out there that mates is helping, but there are many MANY beekeepers who import the packages every year to replace their losses, so I am fighting a battle I cannot win over the course of time, until those other fellows/gals quit beekeeping, die, or wise up and import their own resistant stock.
Treated bees thrive, untreated bees die.
The "natural" way is foolish.. allowing bees to die because they are not resistant makes no intelligent sense to me. Why would you not treat them, and replace the queen? In six to eight weeks there wont be any of the old progeny left, then you get to see if the new genetics can survive, and all you paid for was the queen.. I guess if your rich and dont mind buying packages or nucs every year.. I'm not rich, so I think I will treat when forced to it rather than let them die.