I’ve taken a closer look and I realised I confused “Shared Drives” (which is a G Suite feature) with just shared folders.
I still would’ve preferred if existing customers would have been automatically transferred on to somewhat-equivalent new licenses where they would not lose functionality by “upgrading” to one of the new licenses (e.g. if I “upgrade” from Prime to Personal I lose my ignore rules, which I imagine would also severely mess up the state of my folders if I wasn’t aware of this beforehand), so that we could then safely “upgrade” to get these new features at a reasonable cost (as from a user’s perspective, we had already purchased the base license with features that are no longer contained in the new “Personal” license), rather than paying more than I paid for my initial license to begin with to upgrade to “Developer”.
That being said, I think InSync is a nice piece of software and I like where the actual application is headed. I think they generally do good work, and I get value from it, so in this case I will actually upgrade to the “Developer” license (the “Company” one would have been much too steep a price increase, however).
TL;DR The license change could’ve been handled better for existing customers, but keep up the good work on the actual product.