I've been expecting this news for a while, and I moved to Zen when they changed direction originally. Can highly recommend it as a near drop-in replacement for Arc, albeit built on Firefox.
It's picked up all the most important parts of Arc's design while leaving behind the bits that were questionable (such as TBC's decision to not have bookmarks) and at this point it's pretty solid.
I had been continuing to use Arc for the odd site that insists on something Chromium-based (usually without good reason) since it's the only chromeclone that feels somewhat at home on macOS and hasn't succumb to an ugly generic flat look. It'll be missed.
For a while Arc was my main, but I switched to Orion when it was announced that Arc was going on maintenance mode. Since then I've waffled between Orion and Safari.