See: Will latest 64-bit Haiku nightly builds run 32-bit apps? - #3 by michel
Also, GCC2 32-bit support ends after Haiku R2 release.
As for BeOS, we can run BeOS in a VM preserving use of all legacy software and development tools. Also, installation to x86 physical hardware.
Haiku x86 (32-bit, GCC13) runs most ported BeOS R5 and open-source desktop software. So, it will exist as long as someone maintains a snapshot of it.
So, no major worries…