I think this is possible, remember that the newest system evolved from the old and traditional programming languages. But the problem is that is it going to be complicated if we are going to used those older systems. I still remember programming Foxpro in the mid 90's with all those drop down menus. And then Visual Foxpro come in, similar to C->Visual C->C++ Object programming. Doable but not advisable, IMHO.
It might be possible, although not entirely feasible. Since older systems have many limitations (low RAM, sluggish CPU, etc.), cryptocurrencies will be unable to process a substantial amount of TPS on the network. This is will only work for learning/educational purposes than anything else. I'm guessing that third-world countries have at least "modern systems" that are compatible with today's crypto standards. If that's the case, anyone can still use crypto without breaking the bank.
I'd be surprised to see an implementation of Bitcoin on older programming languages like BASIC, COBOL, or even FORTRAN. Running Bitcoin on MS-DOS or even Windows 95 through Windows ME, could further spur the adoption of crypto worldwide. I'd imagine that block propagation and sync times will be even slower with these OSes, but still practical to send/receive crypto transactions with them.
At least, the idea is there. Making it a reality is another story. As long as people in even the poorest countries are able to use crypto for daily payments, nothing else matters. Just my thoughts