Disney acquired the Firefly IP when they bought 20th Century Fox last year. Firefly, created and showrun by Joss Whedon, ran for fourteen episodes in 2002 and a sequel movie, Serenity, was released in 2005. Although the show was cancelled due to disappointing ratings, it picked up a long tail on DVD and Blu-Ray, and Fox several times subsequently noted that cancelling it had been a mistake. Fox had considered resurrecting the show, but these plans seemed to fall through given the company's complex relationship with Whedon (especially after Fox developed, made and cancelled another Whedon show, Dollhouse, a few years later) and the patchy availability of the show's stars, most of whom have gone on to successful careers elsewhere.
The franchise has continued through comic book series and a superb board game, but a full-blown revival has seemed unlikely for some time.
However, the rumours suggest that Disney is considering rebooting the series from scratch as a somewhat more family-friendly show, perhaps in the vein of The Mandalorian, and tapping the same vein of space adventure. As a result, the rapist-cannibal enemies, the Reavers, are unlikely to appear and the prominent character of Inara, a courtesan, likely to be eliminated (or retrained in a different role).
I find this rumour dubious for multiple reasons. The first is that Firefly's fanbase remains, despite the passage of almost twenty years, both voluble and passionate. Rebooting the show from scratch and dropping the previous actors and continuity would go down very badly. The second is that Firefly's universe was designed from scratch to be slightly more morally murky and complex, and that's part of the show's appeal. Making it more PG (or PG-13, if you're in the USA) seems pointless. Also, whilst Firefly remains a cult hit, it's still very much not a mainstream show. The people who will be most excited about a Firefly reboot are Firefly fans, so alienating them by ditching the previous storylines and cast and crew is particularly self-defeating.
If the show was to return, bringing it back as a next-generation continuation in the same continuity with as many of the actors returning as wanted to, but with new characters doing the heavy lifting, would seem to be a much more sensible idea. This kind of project would probably not be suitable for Disney+, but could be a good match for Hulu or FX, where Disney's other non-kid-friendly properties are headed.
That said, Disney are clearly going to want to take advantage of their vastly-expanded portfolio of IPs, and Firefly would be a reasonable choice if they were looking for a science fiction franchise that hasn't already been over-exploited to the hilt. Disney might also feel that, with Joss Whedon's credibility and reputation at an all-time low, they can get away with a reboot without his involvement at this time, which was not the case a few years ago.
I'll keep my ear to the ground on this one, but I put it in the "possibly but unlikely" category for now.