Replace instant hot with standard water heater?

Good question, I've wondered how hard that would be. If my tankless ever quits, I'd seriously consider putting a conventional in. The dimensions appear to the the same, the issue might be whether the wires to the control panel are compatible since the control panel would be different.

My compartment door might need to be replaced since the exhaust protrudes through a large hole in the door, and I'd have to add the bypass valves since the tankless doesn't have them.