I replaced it with a MacBook Pro several years ago ... but my (Wall Street™) G3 as a matter of fact is still running ’round here as a graphics rendering server-farm participant.
Apple did break from the OS9 world, and fully-embraced Unix (Mach ...), as they continue to do today. This system is fundamentally a Unix, and, FYI (now that the PowerPC chip has been replaced by Intel), modern hardware can run [Windows-whatever | Linux | what-have-you] splendidly in a virtual-machine.
Well, you have choices now. As for me, I proceeded with Apple’s new chosen course, formatted all my systems to use case-sensitive file systems, and, as needed, bought virtual-machine monitors (VMWare ...) under which to run [Windows-whatever / Linux] as VMs, using FireWire/USB-2.0 attached external disk drives as SYSRES volumes ... (oops, I am revealing my mainframe heritage) ... as-required. And that is how I make my living today. Your Mileage May Vary.™