I get the appeal (and the 60 years of accumulated technical skeletons, and the business and legal necessity) of keeping all of the airline’s segments coded as t

I get the appeal (and the 60 years of accumulated technical skeletons, and the business and legal necessity) of keeping all of the airline’s segments coded as the same carrier and notionally able to connect to one another. I do wonder, though: in your scheme with a notional “DL” range and a notional “DZ” range, would it be feasible to partition the real-world flight networks in a way that keeps all the tickets as “same-carrier” according to the legacy logic? That is, could you partition the flight network such that nobody has purchased or ever will purchase a single ticket that spans flights from both ranges? Assuming maybe that a significant number of “backbone” flights (e.g. between hubs) can themselves be “codeshared” between the new DL and DZ ranges. If so, how much new flight number space could you buy, considering the tradeoff between “codeshare all the new DL/DZ flights” and “free up the most new flight numbers”?