Congressionally designated wilderness and areas covered by the roadless rule are not synonymous. Rescission of the roadless rule would not impact areas within wilderness, but could impact areas adjacent to wilderness.
In a very broad comment, areas in many forests were selected for inclusion under the roadless rule for various reasons including a lack of merchantable/desirable timber, technology didn't exist to extract timber, soils/geology prevented roads from being constructed, and/or terrian was too rugged.
It seems likely that a rescission would result in a very small amount of additional timber being cut without incurring a significant financial loss. There are likely areas/forests where this will be less true, and maybe others where this is an understatement.
More roads always equals more pressure.