To whom it may concern: Asus software engineers were busy and they released Oreo: https://www.asus.com/de/Phone/ZenFone-4-ZE554KL/HelpDesk_Download/
For me I'll wait for some answers about compatibility of TWRP and the possibility to root. At present I run rooted Nougat Version WW_14.1064.1711.96 (TWRP 3.1.1 with Magisk V15.2, XPosed V89 and Gravity Box [N.] V 7.0.6). Never change a running system if you don't feel the urgent need
For me I'll wait for some answers about compatibility of TWRP and the possibility to root. At present I run rooted Nougat Version WW_14.1064.1711.96 (TWRP 3.1.1 with Magisk V15.2, XPosed V89 and Gravity Box [N.] V 7.0.6). Never change a running system if you don't feel the urgent need