In old growth, in the climate of five hundred years ago, forest fires were, indeed, part of "the natural process." 

But now, climate change and 100-plus years of industrial logging and tree plantations have created a world in which nature, in the sense you mean it, has ended.

Nature is not going to fix this, not without human help, although the entire history of human silviculture will have to be reconceived to be of any use.