I believe no. As far as I understand RedHat already provides user space "iptables" utility which simply converts any input/output to/from nftables, so there is no kernel iptables in latest RedHat.

Many distro default to iptables-nft, RHEL 8 went further and is not providing iptables-legacy binary at all. RHEL 8 still has iptables in the kernel, I think to allow container sidecars to still work with iptables-legacy.

APIs get removed from Linux all the time. Off the top of my head, here's one: https://man7.org/linux/man-pages/man2/sysctl.2.html

> This system call no longer exists on current kernels! See NOTES.

Before iptables there was ipchains, and before ipchains there was ipfwadm.

I don't think you can still use all of them.

Are you sure?

As far as I understand, it may happen that everybody stops using the old interface (the distros choose what they compile into their kernels, I guess), and after a few years of that the kernel maintainers may decide to remove the old code, assuming it wouldn't be too much work. Don't know how likely it for this to happen in the near future, though.

This scenario isn't impossible, but 'a few years' would be more like 'decades'.