I don't think that separates will every disappear. What I feel may happen is active speakers with the centre channel or a smaller hub wirelessly transmitting audio to all the speakers around the room becoming more common place. I think Sony have developed a budget solution of this kind recently
I know those who enjoy both stereo and cinema will still use very good avr or a dual system which means they will have more boxes whilst keeping the same amount of speakers around the room
I suspect Atmos will evolve like surround sound and become less focused allowing easier placement as it was before Atmos came about using the simple (so long as its somewhere near, it'll work principle)
For soundbar's, are they here to stay? I can never see them disappearing either. You may also see a bigger polarized evolution of them with the cheaper ones offering the basic's plus Atoms (as it will be less focused) and then those like separates who have/want to use a great soundbar employing bits of the active speaker solution for the front 3.0.2 and using wireless rears for 2.0.2 for the rears leaving a respectable woofer to fill in the 0.1.0 as we are starting to see
As for speakers, will we see more dedicated speaker including upward firing speakers like you see with the
Klipsch R-625FA being incorporated in all types of speakers. That's something to keep an eye on, but as many people enjoy upward firing speakers the least and already place them as Atmos Highs (the less focused route as I've mentioned above), I suspect it'll be a small niche market (which ultimately may find more ground if people upgrading from Atmos soundbar's which employ this solution)
The other side is if people are happy to purchase many speakers and scatter them around the room, then the manufacturers are not going to change the formula as it's been working for the 30 years I've owned cinema