I see the benefit of an ACKS 2.0 in consolidating the tweaks from the varios Axioms articles in the same place, plus a few tidbits from HFH such as Alchemmy adding to magic research rolls for potions, critical hits on 10 over roll, etc.
I converted attack rolls to a d20 roll + modifier vs ACKs AC +10. It makes monsters and NPCs easy to write in short hand (e.g. sword +5 1d6+3, or 2 claw +2 1d6, 1 bite +2 2d6). I think that this is not a structural change, but a cosmmetic one.
I do not like the idea of converting ACKS saving throws to a d20 roll + mod vs. various DCs. This is a structural change. In my experience with 5e, it greatly effects scaling. As an OSR option, if the DC was a static level (like the target 20 system), then it is mathematically the same as the current system.
A simplification of the ACKs save system also effects class balance. My players, completely on their own, have noticed the class distinctions in saves and adjust their strategies as a result : Poison? - have the cleric rush in; Magic? - send in the mage, etc.
If there is a vote, I say focus on new content and work on modular rewriting of core sections to include Axiom and new content material appropiate to the sections along the way. This would allow playtesting and comments. You could publish either as Patreon content or piecemeal as pdfs for sale. Once enough sections were completed, you could launch a kickstarter if there seems to be enough interest. That might be a more sustainable economic model, which is important to me as a consumer to ensure that the game continues to grow and be supported.
All that being said, an economic system add-on for 5e could be a very sucessful product. It should include an alternate XP for gold system, and an explanation of player selected balance (i.e. the players deterine the level of risk/reward based on in-game fiction - the deeper/farther you go, the more risk). Without those elements, the basis for the ACKs economic system becomes a little skewed.
A domain management system for 5e would also work, especially if you pared it with a software product that created a UI that combined a hexographer style mapping system that does all of the math and rolls for you. (I keep holding out hope for something like this for ACKs, but I realize that the market just isn't big enough for the development cost - so back to the spreadsheets I go)