Personally, I'd expect a few good years of stewardship, and then a decline in investment. I can only hope there are enough community members to keep things going by then.
I used Texmacs all through my Master's degree. I loved it because it was excellent for quickly writing math, and building tables (I had to do this often). It would not have been excellent if I hadn't dedicated time to learning the keyboard shortcuts, but once I did, I could write math faster than writing it, and much faster than writing it in LaTeX. In timed take-home exams, I would just write the whole exam in texmacs because it was the fastest way for me to work.
To a lesser degree I also appreciated that the files have a similar feel to XML; I think it makes a lot of sense for this type of document.
I remember hearing about the macro system, but never looked into it. It sounded neat though.
When creating a technical document these days, I'd probably reach for typst though.
As a Kagi subscriber, I find this to be mostly useful. I'd say I do about 50% standard Kagi searches, 50% Kagi assistant searches/conversations. This new ability to change the level of "research" performed can be genuinely useful in certain contexts. That said, I probably expect to use this new "research assistant" once or twice a month.
Tried it out on Linux. Worked better than I expected. Sites that are text heavy render well, and quickly. Sites with more "customization" sometimes struggled with rendering; stuff all over the place. Memory usage seemed a bit higher than Firefox with the same tabs, but not out of this world higher.
I would love to have something like this for all the chores around my house. But I also have serious reservations about the increased level insight into my private home life this could provide to the manufacturer. Look at cases like the ring camera security violations [1]. A moving robot could be an order of magnitude more invasive of your privacy. If I were to purchase this, I would want serious privacy guarantees.
I watched the video on the open source maintenance fee page (https://opensourcemaintenancefee.org/) and it explains that the fee is for 1) people/orgs who make revenue from the open source code AND 2) want to interact with the GitHub project (e.g. open issues). You can however 1) make revenue from the open source code, but not interact with the GitHub project without paying the fee.
For instance, if I'm an organization that wants to use this open source project for free, I can download and build the code, but not download a GitHub generated release binary.