TOA has made preamps and power amps for commercial/industrial applications with interchangeable modules, based on what was needed- the preamp modules could be bought with a variety of input jacks and circuitry, power amp modules came with different power output. I saw these more than 25 years ago and with miniaturization, circuit density can be maximized. Pre/pro in one box, vertically oriented power amp modules in another with a quiet fan and properly designed ventilation. If they really want to made it robust, the power supply could be in another box with a power cable going to the pre/pro in the main area and the power amp can be placed with the other pieces that don't need to be accessed in normal operation.
If a module fails, it's removed and replaced, rather than removing the whole piece and shipping a large, heavy item that will likely be mishandled and damaged.
Now, if we could only make people understand why this would work and accept it, we might see an end to the crap that's being produced and shoved down our necks.