Do we know their surrender will be accepted? I bet most of them will be made example of, no? If a peaceful surrender is possible and they join Venatori then yes we have a serious problem here.
This is not about the conditions of society, its a desperation act with death or tranquility as alternative.
Well in DA2 there is a mention of Sanitarium Bartrand goes to if spared, I don't see why Templars can't go to such places
Because they can't be cured, and again, lyrium cost a lot of money. The Sanitarium won't manage to acquire it, so they'll constantly suffer until The die.