I really feel I could write War and Peace about this, but I'm going to try not to.
Sonor need to tick off a few basic things:
Top of the list, financial stability, especially at the moment with post-COVID inflation, volatile shipping globally and world domination fantasists making stability between countries a daily roll of the dice.
Top tier German made products that continue to set a benchmark globally and continue to either offer things others do not, or offer things others also do, but just do it better.
Reliable reference to their heritage, but IMO not by doing what Ludwig has done, which is essentially to get back on the scoreboard after making some bad decisions, making what they made in their heyday again, just (marginally) better built.
The 'superiority' of their products be based on truths - excellent quality, genuine research, proper design engineering in evidence in their manufacturing, science where necessary - NOT on marketing hokum (I'm looking at you DW)
Gateway drugs, to get new drummers into what Sonor is all about
It's the top one which I think is currently getting people out of whack currently. I can see why everyone is saying that the Momentum series is too safe, too much of a 'parts bin special' and too much like 'saving money' rather than anything new, but in the context of where we are currently, I'd question the financial savvy of any company boss re-writing the products from the ground up. We're not in late 80's Germany when all German manufacturing threw money hand over fist at making the best products money could buy. It's not exciting, but I'd rather see a company play it safe and still be here for their 200th anniversary than revolutionise things and be gone in 5ys.
Then when you look down the rest of that list, they're pretty much already doing it. This is why I think some of the criticisms that have come out this year, I can see where they come from but in many senses, they're not valid.
But to play the game, what could they do?
Continue to lean into the limited run (Craftsman, 150th etc) idea - like it or not, every high value, desirable brand is playing this game. Generate more demand than there is supply and it continues to elevate your brand as luxurious. There are pitfalls to this though, some brands are doing it to almost everything - there's nothing particularly 'halo' about 250 cheap kits in a specific colour when that's probably the actual amount you'll sell globally anyway. That does more harm than good to the brand name. Do not go down the Ferrari/Porsche route of only being able to buy the very high end stuff if you're on a friends list, one which you had to buy your way onto with 20 previous purchases first. Sonor are already navigating the opposite ends of this spectrum pretty well.
Update the made in Asia products. They already turned the right corner by setting a quality level they won't drop beyond, that's serving them well. IMO the lugs look cheap and a bit 'jelly mould copy of the real thing.' I'd look at updating those to make them a little 'sharper' looking, retain TuneSafe but make sure they're still differentiated to the German ones somehow via a method that isn't 'make them from pot metal.'
Re-factor the Asian made series to cater to who is buying them. Those with a tighter budget, those who are entering the Sonor world, and more importantly, those who are well aware of the Sonor brand, but who want a cheap gigging kit. I think finishes, shell sizes etc. could be tweaked to make some of the Asian made gear irresistible for seasoned gigging types.
Dare I say an Asian made kit with roundover edges and thin shells for all the vibey jazz heads playing five nights a week in little bars?
Lean into what makes Sonor snares great. Outwardly they look like parts bin specials, with a fancy paint job a lot of the time. If I looked at a Jost Nickel snare, nothing about it stands out beyond it being a standard shell with standard parts. Yet once you own a few Sonor snares, you realise what's magic about them is the weird 'sum of its parts' effect that goes beyond the spec sheet. I've never really seen them ever talk about that and I think it's their greatest stand out difference. Keep the Prolite brass, but explain why, somehow, it's better than a brass Kompressor. Don't vanish too far into marketing bullshit.
Even if it's only in small numbers, reintroduce parallel action snares
Include Vintage Series lugs, bronze shells and a few other choice options into the SQ2 configurator.
Update the veneer options, they need less 'billionaire's boardroom table ostentatious' veneers and more 'Japanese/Scandinavian minimalist classy' options. I'm personally a big fan of the heavily figured/quilted looks, and of the Japanese Sen that Tama use.
Introduce the option to stain a veneer choice from a limited palette.
Also introduce torched options to some select veneers. Tama and BDC doing it well, Craviotto and N&C are not.
Call it SQ2+ if you like, but for silly money, actually let people order whatever they want. Yes I do want a 7.25" depth snare. Yes I do want to send you a tree from my family's yard and have you turn it into the outer veneer. Yes I do want a 20" floor tom, or silly deep or silly shallow floor toms. Yes I do want roundover edges on my 12mm thick floor tom.
If Momentum Series works, have another, with reduced options using the vintage shell recipe with rings.
Have a crack at the one shell recipe they haven't taken on yet which is still so desirable - 3ply with rings and rounded edges (and potentially two woods) and take on Ludwig and Gretsch and everyone else at their own game.
Try a kit made from a genuinely hard wood, call it a Craftsman run if you like, but let me see what Sonor would do with some jarrah or something like that in 10mm thick layup.
Gigging hardware
Signature Series style high end hardware
I'll stop now but I could go on... 
DaveInNZ