Many chip manufacturers quickly rushed to make high-integration chips for the IBM PC market. Serial ports, parallel ports, game ports, floppy drive and hard drive interfaces. Any combination of some or all of these functions. When the ISA bus became obsolete, the chip manufacturers left the market just as quick.

For example, I have an ISA bus multi-I/O card with serial, parallel, floppy and hard drive interfaces provided by a single chip - the Acer M5105. Interesting but not only can I not buy one on eBay, I can't even find the data sheet. No point in designing projects that use unobtainable chips.

However, chips that provide PC-compatible serial interfaces are still made. They are pretty capable devices, and there had been no market demand to drive the evolution of devices like the 6850, SIO,  and so on. 

The 16C552 is one of the few chips still made that have an LPT port. Even if you don't have a Centronics printer to talk to, an LPT port can provide a little parallel I/O to play with.

At the time of writing, the 16C552 is available from Mouser and Digikey.