I'm part of Team Red, working on Rebol's successor (https://www.red-lang.org/). We have a number of old Rebolers, but also a lot of new faces, and we're having a great time carrying the torch forward. We still have a lot of work to do, but by the end of the year we should have feature parity with R2, not to mention all the new features Red has, like a compiler, reactive system, Android support, and native GUIs.
It's very similar to Rebol and is under active development. If you like Rebol and haven't tried Red, it's worth taking a look:
which is a spreadsheet in 17 lines of code using the inbuilt reactive system.
In fact there was a Rebol conference only last month - http://2019.reb4.me/