I think we might be overstating the impact of this change. We're not going from 100% visibility to 0% visibility. Two years ago we were getting 0 decklists each week from WotC, now we'll be getting maybe 3 to 6? Nowhere in the announcement did they mention anything about changing reporting for Vintage Challenges, where our most interesting data comes from anyway.
Note that the stated goal is that they show a wider variety, and higher number of decks. In standard they expect these changes to pretty dramatically increase the amount of decklists seen each week. If it turns out that these changes decrease the number of decks released in vintage, it's totally plausible that they could use different definitions for "distinct decklist" in different formats - the fact that they're releasing vintage on a different schedule than standard already implies their up to the possibility of tweaking numbers on a per-format basis. As they said in the article linked:
"We don't necessarily believe we've found the sweet spot just yet"
And while this change as stated will definitely reduce the variety of similar-but-strategically different blue archetypes we see, it will increase the visibility of decks just outside that 20-card difference limit, things like BUG Control and Ritual Combo, the Hate Bear decks we were seeing a few months back, and stuff like Saturn's Helm of Awakening deck he keeps spiking Challenges with.
There's also a non-zero chance that this change incentivizes people to run sufficiently different cards in order to increase their chances of getting published decklists. I think it's fair to interpret that as a good or a bad thing, but there's potential upside.
There's no doubt in my mind that this change will make the data we have less accurate, but it's clear that WotC has different priorities than accuracy, and those priorities aren't in and of themselves bad.
In the worst case scenario they fail to adjust the formula to meet vintage-specific requirements, and we end up going down to 4 or 5 published decks a week. 1-2 blue deck, 1 shops deck, 1 dredge deck, 1 other. Vintage was fine with 0 MTGO decklists a week, and it'll be fine with 5.
In the event that these changes result in genuinely important technology and/or decklists missing from the reported results, I highly suggest you just post those decklists here instead