I personally think it can actually be cured but it requires two things, a very strong fungicide to kill it in the plant and an extreme disinfecting of the environment, which requires bleaching every surface in your home and a heavy shock treatment with an ozone generator to kill all the airborne pm spores and the ones you missed with the bleach cleaning.
I have one friend who followed those steps about 8 months ago and has not seen pm since, and another friend who just did it a month ago and is now waiting to see if it lasts...
Another important thing is to run a dehumidifier and keep your humidity lower than 50%. You should also foliar spray your plants with neem while in veg to protect them from any new pm spores from attaching themselves to the plants.