what makes me sad is that while Apple has done very well with these major transitions, it leaves behind instances where (for me) a completely unique application

what makes me sad is that while Apple has done very well with these major transitions, it leaves behind instances where (for me) a completely unique application gets left in behind. I currently maintain an only system 7 computer for software that is incompatible with system 8 or 9. A MDD G4 running System 9 for software that won't run on OSX, and a Mac Pro running 10.6.8 to run PPC OSX application (through Rosetta.) I haven't upgraded to Catalina because I have some applications that will never make the transition to 64bit, and now I'll have to maintain something to keep intel compatibility on the table (assuming Apple EOLs Rosetta 2 like they did Rosetta.)