the pace PRC does this already, its main market was military mobile repair vans or something
the biggest problem with modular products is they don't follow advances. you would need to have alot of foresight to make a modular chassis that ages well.
soldering is a constantly evolving field where I am sure more gadgets will get made and become popular to do things.
and systems engineering to allow for upgrade is hard, because you end up with scenarios like "THEY MANAGED TO PUT 25 AMPS IN THAT?!?!" when you have room for 10 amps. It turns into mechanical engineering nightmare where your trying to get stuff to fit in a known from.
I'm not doing a gadget, so it's made to be durable, every instant Tips work more or less the same, it's not because you see a lot of new product with new design, that it means the technologies is New. But adapting the power supply for example is not too complicated if you consider letting some room when you design it. It's also possible to get some external part in a box below the table for example, but it's more like if I decide to use a big old transformer that I know can have some advantages some time. You can do what ever you want with the circuit and the box its open source.
take a look at the PRC2000, its not a gadget, its a $10000 soldering mainframe
https://paceworldwide.com/prc2000-th-through-hole-miniature-microminiature-electronic-repair-stationIt does it all but its not really 'cutting edge' on all its tools.
Their good for aviation and military wiring that has alot of weird medium precision interfaces, shields and has extra big parts for durability. It does enough special stuff that its not gonna go away in utility.
But again, if you make high end highly integrated tools, only the government is really interested in that for tactical use. You put that in a van that drives up to a aircraft or tank to do some quick repairs lol
And linking a soldering iron to literary anything else in the lab means you need a backup iron unless you wanna take some time off, its like the most critical thing there. managers know a complex multi function tool is gonna go down and they want as little down time as possible, so they prefer independent tools. However putting all that crap in a mobile repair van or tactical repair center (tent in desert) is difficult enough that the PRC2000 is a viable product despite its complexity, though I would not be surprised if they glue on the accessories lol
how are you gonna sell some clunker compared to a TR80 USBC soldering pen that I can put in my coffee mug if I am just a generic hobbyist??
Study pace product line, they had all sorts of combo machines over the last 30 years. most of them are hard to enigneer and have weird custom parts (graphite vane pump, resistance transformers, etc).
Like for hot air stations, right now the "keys" are
1) integrate air pump into machine for a "pen" tool, no fan in handle
2) very fast warmup and cooldown time
3) precision control, remote sensing
4) quiet
basically all of those are thermodynamic engineering problems, that require physics level approach, nothing can be done for systems enigneering here to improve any of it. The physics end of the tools need improvement, no one cares about the back end, the electronics are already way better then the "physics devices" that do the work.