We were fighting these beetle infestations back in the 70's when we were worried about global cooling. The beetles are not new, their presence is not a result of global warming but rather of our meddling with natural burn patterns for so many years.
In un managed forests a fire sweeps through every couple decades killing off the beetle killed trees and most the beetles in an area, the healthy trees are singed but not really harmed and are thus protected by the killing of most the beetles. In managed forests where we basically stopped all fires as soon as they started, the beetles killed a few trees, then a few more then a lot more and so on. After several years a dead tree might finally fall over allowing new growth to come up in it's place but mostly they just stood as forests of reddish grey dead trees.
Now we try to allow some burns, manage others and intentionally set many management fires each year. But thanks to the decades of mismanagement managed and natural fires are frequently getting out of control due to the massive swaths of beetle killed trees.
Once burned those forests will at last begin to naturally regenerate. Not right back to the forests of standing conifers, but through the natural stages often first of grasses and shrubs then deciduous trees like quaking aspens and scub oak and then over decades back to conifers. Depending on the water cycle in the area. Other areas with more moisture will get back to the conifers more quickly.