Current Itch mods and Workshop mods definitely won't work together. The Workshop update will bring a lot of changes to the base game's code that require every mod change how they do certain things.
I know a couple people that have said they aren't gonna port, but I also know someone who is willing to port those people's mods for them. I'd say it's up in the air.
You may have to wait a bit to get your full catalogue back, but I think you'll at least have most, if not all, of it back eventually.