Redoing Sub floor in 1920 home

I have what appears to be pine plank subfloors in my 1920s home. I want to redo the subfloors to add insulation between floors, but am now having second thoughts. Why? Because the sub floor looks to be in good condition, but I do want insulation between floors.

If I replace the old subfloors what should I consider if anything? Or is it really just a matter of swapping one for the other