GP Flash was actually fairly interesting as an exercise in how to break the most broken combo Wizards has ever made.
But we don't have a GP coming up, and most cards on the banned list don't come anywhere near the power level of Flash.
I look at Vintage with goddamn envy. Wizards is constantly tinkering with the Vintage list in order to try and find more dynamic configurations. Sure, some of their moves, like unbanning Gush, turn out to be bad ideas. They lead to a brief period of dominance and then they get banned again. Is it the end of the world? No. It just means anyone with a double digit pulse can actually follow and enjoy the format.
What evidence is there to suggest that anyone would be lost? Does Vintage lose people, or has it attracted more people with the shaking up of the format? Did Legacy lose people over Flash or did it draw attention to the format?
Here's the thing;
When they first separated the list, everyone- and I mean
everyone, whether you were for or against the changes- said the cards they chose to ban and unban were random as fuck. People were deeply upset that they banned cards that weren't even a blip on the 1.5 radar like Oath, Land Tax and Hermit Druid, while leaving off tutors and fast mana that enabled Tendrils-combo to exist in the format for the first time.
Even Wizards themselves
said that the list was just an asspull, trying out a few things and saving tinkering for a later date.
It's five years later. Legacy has, by my count, endured a total of five changes. One of those was the banning of Flash, a card that only existed, functionally, for a month. One of those was the banning of Imperial Seal, which didn't actually legally exist in the format prior to being banned. One card banned, Shahrazad, saw no play and was banned due to speculative hypothetical asshattery. Two cards unbanned, Mind over Matter and Replenish, have seen scant fringe play.
No other format with a wide cardpool has received so little development attention, even the casual formats like Prismatic. Legacy "works" in that the same deck that was the best strategy two years ago is still the best strategy, and other decks have some relevant chance of competing with said best deck.
It's also boring as fuck.
Nothing bad would happen from three months that are actually distinguishable in some way from the three months preceding them in Legacy play.