Turtle Controller: Your post is wholly disingenuous and you know it. You are trolling. The arguments in favour of MAN supporting a whole-plane cargo capability were NOT as you state, and I invite you to revisit said "long essays" to confirm that.
Now. About DSA. Why did it really face closure? Because it certainly wasn't because of their modest but welcome cargo operation.
Wizz Air had pledged to establish a base there with four aircraft committed and an eventual ten envisaged. Then they reneged on that deal AFTER Peel had committed a substantial sum to arranging facilities to Wizz Air's liking. Since you are clearly unaware, TC, Wizz Air is primarily a no-frills airline focused on passenger business, NOT CARGO.
FlyBe also established a base at DSA. But then they went bust. A major blow to DSA's business plan. Since you are clearly unaware, TC, original FlyBe was a passenger-focused airline, NOT a whole-plane cargo operator.
In earlier years, both EasyJet and Ryanair were persuaded to give DSA a go. They both pulled out. This was a major blow to DSA. Since you are clearly unaware, TC, EasyJet and Ryanair are passenger-focused airlines, NOT whole-plane cargo operators.
The cargo operation at DSA was a welcome revenue stream but NEVER the raison-d-être of the airport. And that is what it should be at MAN too. Nobody on this forum has argued otherwise.
So DSA presents it's owners with a conundrum. All the no-frills carriers which could reasonably have been pursued by DSA have tried and failed. On more package holiday focused business, they host a stable and successful TUI base, but that is not sufficient to support passenger ops at DSA without considerable throughput by others. Only a handful of low-yield Wizz Air rotations per week use the terminal alongside these. There is little chance of attracting a network carrier such as KLM with the issues ongoing at AMS. Jet2 would be ideal from DSA's perspective, but the carrier itself has it's HQ at nearby LBA where it dominates, it's largest base at MAN and a healthy operation at EMA. They've got the region covered without venturing into DSA.
DSA has other operations onsite including 2Excel Aviation and the NPAS. But their contribution is insufficient to keep the airport afloat either.
But the real problem facing DSA as a perpetual money-pit airport is that the land it occupies is so perfect for profitable alternative uses. I'm guessing - but cannot confirm - that the airport will be considered brownfield land. It is relatively central to England and located adjacent to the M1 corridor. PERFECT for warehousing, logistics, and light industry. Businesses which will ultimately provide the area with substantial secure employment - and not just on a seasonal minimum wage basis which accounts for many of the posts at the existing airport operation. Local councils will make sympathetic noises at this time, but when the outcry dies down they will welcome those new employers and the windfall they bring with open arms. It simply makes economic sense. And DSA as an operational airport simply doesn't.
Finally, Turtle Controller, if you would like to apologise to the regular posters on this thread for your unwarranted and ill-informed attack, feel free to do so any time now.