The iPhone 8 should have never been released just like the 5c. The X drew an X on the 8. There is too much overlap and what's the point paying another $700 for a HD iPhone? Less RAM at only 2 GB. No Telephoto. Smallest battery with lowest endurance. X forever killed off 4.7" iPhones.
Entry level - SE/compact series but Apple will only update it every two years.
Mid-level - The current LCD models. The X is currently for the extravagant spending like people who spent $600 for a PS3 or $3000 for a MBP last year but the X (5.8") will reach this point once Apple phases out LCD models within two years.
Premium flagship - This is where the XL model will dethrone the current X within 10 months. Samsung does the same thing between their Galaxy S vs Note and LG does the same with G-series vs V-series. This will go for a minimum $1099+ for the base model. It will offer more RAM and longest endurance again. Might even include PiP, split-view, and homescreen landscape mode again.