I am for sure not keeping my pre-X phone.
Like you I have the 8 plus. I originally ordered the X, but when I realized that the net screen will be less than the 8 plus (especially in the width) i canceled my X order and got the 8 plus.
But I have to say my 8 plus and wife's 8 had some of the worst cell phone receptions of phones we had over they years. When I got my first mobile phone in 1990's it was brick with > 1 lbs, had to be charged several times a day and talk time was something like 20 to 30 minutes (which we mostly didn't need since it was hugely expensive). But in 1990's and early 2000's the number one focus of testing was how good the reception is and if you can make calls in remote areas with low signal.
Today the focus is on how smart a phone is (in many cases much smarter, than the owner), but it seems the basics have been forgotten. I want to be able to make and receive calls as well send and receive text in low signal areas (which I am frequently in as an outdoor enthusiast).
For me between 3G, 4, 5, 6, 7 Plus and 8 Plus the 8 is clearly the lowest performer in that category. With the forecast of the new phone having improved antenna and modem, this will be my main reason to upgrade to the XS plus.
Than add the this time the really bigger screen, Face ID and better camera and I give you a clear I am in ...