So the writing is on the wall the original hardware may still work but many will not be able to hook it up. TVs are dropping the antenna rf port and analog av ports meaning if you don't have an HDMI or compatible signal you won't be able to hook it up to a modern TV. While there are clone systems that mimic the system there is nothing that gives real accurate low latency authentic hardware representations. So what can be done when no one is making these chips and they were never meant to be used with digital outputs. The answer is FPGA a chip that can literally change it's internal connections to mimic actual hardware and clone actual chips so you have a low latency authentic system that acts almost identically to real hardware but can be reconfigured to run on modern TVs.
There is an open source project to resurrect and preserve gaming platforms in FPGA form that can be used by the community to create hardware projects commercial or personal. The name of the project is the MiSTer FPGA and they have working Atari 2600, 5200, Nintendo NES, Sega Genesis, Arcade Boards and other platforms. There are no 7800 cores but more than half the work is already done given the processor and 2600 chips are already there. Without someone's help the 7800 may fade to even more obscurity and will not be playable.
Here are some links for further information:
So what are your thoughts and what do you think the future or fate of the 7800 is?