Not quite... Linux has also deprecated and removed support for processor architectures and devices (though pretty obscure architectures and peripherals such as ISDN controllers) - see https://lwn.net/Articles/769468/
As far as I know, you are free to add them back in whenever you want. Support is removed from the kernel when no one is around to maintain the feature. If a breaking change has to be made and no one steps up to implement it, the support gets dropped.