Is there a need for a new Linux distro?

I guess that depends on what one is looking for. I think that the current selection covers at least 99% of people's needs and wants.

It sometimes makes sense to made a distro that is specifically for new or unusual hardware.

I point to Asahi Linux, supporting Apple computers based on their M1, M2 and M3 ARM cpus is a load of work that is still in progress and sometimes issues are only found when a load of people use it. Eventually the source code that has been written or modified to support Apples relatively-new hardware will reach mainstream distros so people can run Debian, Ubuntu, Redhat etc on an M1 mac with working sound, gpu etc.

If some new RISC-V single board computer reaches the market it might make sense for someone to make a distro specifically for it.

A distro for specific hardware may get better performance by being compiled to use the specific instruction set and cpu features.

Old distros fade away, new distros come in to replace them.

It's a dynamic universe, not a static one.

There's also a smattering of Darwinism there, the good distros survive, the not so good ones die off.

Solutions first need problems.

The wheel can't be reinvented often enough...