> how many new hardwares contain more than one processing core?

Very many ;-)

> Are these CPUs?

Yes, CPU chips today usually come as symmetric multicore. GPU chips have been massively symmetric multicore (100s to 1000s of cores) for even longer time. And then there're SoCs, which are chips that are asymmetric multicore with 1...n symmetric CPU cores plus (for instance) 1...n symmetric GPU cores plus 1...n DSP cores plus...

> Are the single core CPU becoming endangered species?

I'd say yes, except for CPUs for some low-performance niches.

> Eventually, MorphOS should somehow be supporting more than one CPU core
> if that is all that becomes available. ...unless MorphOS Team wants to
> make custom hardware with single core CPU.

Of course it's perfectly possible to just support one core of a multicore CPU and ignore (or better put to sleep) the other cores. At least it makes more sense for producers of a single-core OS to just support existing multicore hardware in single-core mode than producing their own custom single-core hardware.