Each release will only provide support for the previous release binaries. So R1 will support BeOS binaries, R2 will support R1 but not BeOS, etc. However I think this only applies to the same architectures of each release. So 64 bit R1 won’t support any 32 bit binaries, which includes BeOS. Someone correct me if I am wrong.
Of course any 3rd party package for a 32 bit emulator/wrapper on x64 would be awesome!