Thank you SwordGuy and davisgang for bumping that thread!!! I've got two little guys with autism and I'm just learning about all this stuff, however it's tricky because at this point we just don't know if they will have needs into adulthood or if they will be totally independent. The autism spectrum is so diverse!! Even these two are totally different from one another.
The one piece of concrete information I can add is that up to 15k per year can be rolled from a 529 to an ABLE account without tax or penalty. I am in a high-tax state and for now I am continuing to contribute to 529's up to the state tax deduction limit with knowledge that the money can be used to help my children whether or not they are able to go to college.
The rest of my strategy for now is VTSAX and chill lol. My fire plan is quite flexible and I can easily pick up some part-time work in my field if more money is needed. I still need to get on will-making but my brother has verbally agreed to be a guardian if my spouse and I both die. Once they are teenagers I will have better information about whether they will be able to manage money on their own as adults, so I'm going to wait before setting up any kind of trust.