All point and shoot cameras are mirrorless and have been since day one. They are very slow to operate because they cannot focus quickly. Many do not have viewfinders, requiring you to use the LCD on the rear to compose, and in bright sun, this can be a challange.
Several things have happened to improve the P&S cameras.
1. larger sensors means better IQ and light sensitivity
2. Some have interchangable lenses which makes them more flexible over a wide range of focal lengths
3. Novel methods of improving focus speed have appeared, embedding focus elements in the sensor, or using a pellicle mirror to pass most of the light to the sensor, but part of it to the viewfinder. Pellicle mirrors decrease the amount of light going to the sensor, which bothers some, and reflections off both surfaces of the pellical mirror can cause a effect called ghosting, a faint second image displaced slightly from the main image.
4. Electronic viewfinders - they are getting better every year, not perfect, but have advantages as well as disadvantages. They are certainly better than no viewfinder at all.
So, what we are seeing is the industry trying to incorporate all the best attributes of a DSLR without the moving mirror, which is something out of the stone age of cameras, as well as innovating with features not possible or at least not available in DSLR's.
So far, they are a compromise, but good enough so that many will prefer them to DSLR's for ease of use and smaller form factor. They will improve each year as innovative ideas are incorporated.
I haven't yet found one good enough to replace my 5D MK II, or my 7D either. However, as a second or third camera for walk-around or use where a big DSLR can't be used, they fit in very well.