What would be a modern Programmable sound generator?
Other than repairing old arcade machines and a handful of hobbyists, what would be the market for such chip in 2014? 

Open-source VHDL code emulating some such sound chips is available, so you could stuff that into a smallish FPGA (but you can forget about DIP packages unless you can find a PC board with DIP headers on it). 

Learning enough VHDL and navigating (say) Xilinx Webpack is non-trivial though, even though the free software would be sufficient.