I just did my first 7.5 kernel upgrade, and I'm happy to report that the system came right up into the new kernel (the first time that it's ever done so without manual edits to extlinux.conf).
In fact, I was a bit surprised that it booted the *new* kernel. Here is my extlinux.conf:
# extlinux.conf generated by appliance-creator ui menu.c32 menu autoboot Welcome to CentOS-Userland-7-armv7hl-generic-Minimal-1804. Automatic boot in # second{,s}. Press a key for options. menu title CentOS-Userland-7-armv7hl-generic-Minimal-1804 Boot Options. menu hidden timeout 20 totaltimeout 600
default=CentOS-Userland-7-armv7hl-generic-Minimal-1804 (4.14.28-201.el7.centos.armv7hl) label CentOS Linux (4.14.43-201.el7.armv7hl) 7 (Core) kernel /vmlinuz-4.14.43-201.el7.armv7hl append ro root=UUID=eb2c92c6-69cd-4a87-982d-900be79e928e LANG=en_US.UTF-8 fdtdir /dtb-4.14.43-201.el7.armv7hl initrd /initramfs-4.14.43-201.el7.armv7hl.img
label CentOS-Userland-7-armv7hl-generic-Minimal-1804 (4.14.28-201.el7.centos.armv7hl) kernel /vmlinuz-4.14.28-201.el7.centos.armv7hl append ro root=UUID=eb2c92c6-69cd-4a87-982d-900be79e928e fdtdir /dtb-4.14.28-201.el7.centos.armv7hl initrd /initramfs-4.14.28-201.el7.centos.armv7hl.img
Based on the "default=..." line, I expected it to boot 4.14.28-201.el7.centos.armv7hl. Instead it booted into 4.14.43-201.el7.armv7hl.
So something still seems just a bit off.