As an Affinity Designer owner I also use CorelDraw X8 as it has some very powerful capabilities esp. regarding its page layout text handling overall. I am awaiting Affinity Publisher as I wish to see if I can make the jump from Corel to Serif/Affinity (although I may keep CD around).
One of the things that makes me warm to the Affinity range is that in following Adobe and MS, Corel is edging closer to the subscription route. Although I don't think Corel are quite big enough to go subs only.
I notice that on the Affinity web site, it mentions Affinity Publisher will appear in 2018. Whilst I don't expect a definite date, it would be helpful to know if it will be Q1, Q2, Q3 or Q4. After all, Dec 31 2018 would still qualify!