The argument that "magic is a natural part of the world" just results in solidifying the anti-Solas stances.
In real world terms, think of the pre-Veil world as the Ice Age and the post-Veil world as the world after the Ice Age is gone. The Ice Age's environment allowed specific forms of organisms to flourish and the end of the Ice Age brought the extinction of many of those organism or the evolution of those organisms to something else.
Solas, Ancient Elves and pre-Veil world is like the world during the Ice Age whereas the post-Veil world, modern people (modern Humans, modern Elves, modern Dwarves, modern Qunaris) is like the world post Ice Age. Different organisms that evolved under different sets of conditions and in all likelihood, are incompatible under another set of condition.
Solas actions to bring down the Veil to restore the world to its natural state would be the equivalent of an Ice Age Human that managed to survive into the modern world wanting to bring back the Ice Age because back then, cold and ice was as natural as breathing and now, its been severely restricted to specific seasons and specific locations.
Which means those who are against Solas have a very solid foundation to oppose him and his goals since is planning to bring back a set of conditions that they are not prepared for, that they did not evolve in and will mostly die because of it. Can you imagine if some Ice Age Human wanting to bring back the Ice Age because that was the natural state of the world he lived in ? Would you not feel threatened and want to defend yourself and potentially kill the maniac planning this reversal ?
So yeah, thanks for supporting those who wish to oppose Solas' plans and potentially kill him. Cheers. 
Ow, ow, ow... this false equivalency is so bad it hurts to look at it.
Like... comparing situation in Thedas to natural period of glaciation while we have a way more correct analogy to life-sustaining element (even in game Blackwall compares magic to water)???
Not to mention that cycles of planet warming and cooling are entirely natural, gradual (takes thousands of years for the Earth to start cooling or warming) and life has time to adjust to it, rather than be extinct and replaced. I mean FFS, humans DID survive last Ice Age, which happened about 12 thousands years ago, while anatomically modern humans existed for at least 100 thousand years.
Also... "cold and ice was as natural as breathing"? Can't you see just how silly this sounds? How can ice be "as natural as breathing"? The context is entirely off.
Now, I'm not negating that the whole "modern people may or may not survive conditions of Veilless world", but your entire perspective reeks of bias, because you compare Solas's plan to something ridiculous - you intentionally portray "Ice Age humans" as ridiculous in their assessments, since we know that Ice Age has nothing to do with "natural stages" of human existence, nor is necessary for us to survive.
Sadly for you Fade IS necessary for Thedosians to survive - and I mean both living people AND spirits. We don't know yet if cutting away the Fade won't end up bad for everyone in the long run. Way more apt analogy is the one I've done already that compares the Veil to sealed glass-house, or even Greenhouse effect we now deal with - the conditions weed out past life forms and only those able to adjust to them survive, but eventually the glass-house may become so warm it will literally cook everything inside it. We can't rule out that it's a distinct possibility - especially with the Blight always threatening to spill on entire Thedas or attempts of Qunari (and who knows who else) to strengthen the Veil.
That and there's another thing - yes, modern Thedosians have the right to fight those who threaten their world, way of living or even existence... but so is the other side. Just because the world is different now doesn't mean that those unadjusted to modern world have to just lay down and die, especially that we don't know their numbers or relevance for the whole world for it to actually exist, if it actually contains spirits too.
Claiming otherwise makes you no better than what you think Solas is: you only see one side as valid, while deny another the right to live or even exist. I just don't see things that way. If it's an absolute necessity to choose one or the other for it to actually survive what's to come, I'd make that decision, but if there's even a shadow of a chance for modern and ancient world to reconcile, which eventually means saving lives on both sides, or improving it for new generations, most of my Inkys will totally work towards this.