Not too sensible at all Martin, and I think that is what the author of the article was suggesting when he said "they remain highly potent air-to-air fighter platforms and should be able to more than match any adversaries that they might meet in this arena for a number of years yet".
What would be the point of retaining the Tranche 1's if there aren't the aircrew to fly them, or the budget to keep them current?
Surely, the manning plans have been drawn up with the reduced platform numbers in mind. Increase the numbers of aircraft, and adjust the manning level plans accordingly. As the article points out, all of the Typhoon investment has already been made, and all of the operating and support infrastructure will remain budgeted for out to the 2030 OSD of the T2 and T3 aircraft - how much more would it cost for the T1s to ride along on their coat tails? For sure, there would be an economic hit, but I'd suggest it would be relatively minor when offset by the added capability.