The article mentions this, but there are examples of natural turf in cold climates done better than Soldier Field. Lambeau is one of them. I imagine it would cost a lot to retrofit Soldier Field with the technology necessary to keep up the natural turf to those levels. Frankly, I like natural grass so much I'd be for spending that money, rather than putting in more field turf like the rest of the league. I'd like to maintain bastions of natural turf, and I think Chicago is one of those places where it should stay in place --- but done well, not done poorly like it currently is.