Chak-
I don't really want to get into it but from an electronics perspective it would be very easy to design a system of electronic shifters and derailleurs that would work with any number of speeds (up to the precision of your little servos) within some left-right/up-down range (i.e. the cassette would have some maximum width - at least 40mm if you want to do current 11-speed - and a maximum sprocket size - let's say design it to take up to a 50t). Then you just need to tell it the sprocket pitch and the number of speeds and you can put whatever cassette you like on there (assuming that you have a long enough cage). If 13-speed comes out in 5 years with this system you'd just need to get a new cassette and chain and reprogram everything for it to work (as long as it's less wide than the range of your derailleur).
This is not currently possible; i.e. there are only certain combinations of shifters, derailleurs and cassettes between road, MTB, 10/11-speed that work, and so you can't mix and match bits to get the exact setup that you want.
If you ask me Shimano/SRAM probably could allow this right now and perhaps will at some point in the future. If not maybe some computer wizard will write some software to get it to work one day. Or some other company will do it.
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frankenbike
Sell the shifters/derailleur (if it's integrated like SRAM + Shimano ones)/other electronics/software/etc.