A primary character in Star Wars Rebels appearing in Obi-Wan Kenobi is the Grand Inquisitor, who serves as the main villain of Rebels season 1. Reva apparently murdered the Grand Inquisitor in episode 2 of Kenobi, creating significant confusion due to his appearance a few years later in Rebels Canon.
It is very probable that in Obi-Wan Kenobi episode 3 it is disclosed that the Grand Inquisitor is merely wounded. The Inquisitor could recover (with some bacta-aid) and return, ultimately finding Kanan Jarrus and Ezra Bridger a few years afterward at the start of Star Wars Rebels. Considering Disney's incorporation, and sometimes dependence, on the animated aspects of the Star Wars franchise with the development of The Clone Wars season 7 and Star Wars: The Bad Batch, it would be illogical to eliminate Rebels from canon.
Additionally, characters and unresolved plotlines from the conclusion of Star Wars Rebels are anticipated to carry on in Ahsoka, set to premiere next year. For instance, a key villain from Star Wars Rebels, Grand Admiral Thrawn, was referenced in The Mandalorian. Additionally, another original character from Rebels, Sabine Wren, is confirmed to feature in the Ahsoka series, with strong rumors indicating that Ezra Bridger might also make an appearance. This indicates that the canon of Rebels is preserved, regardless of choices made in Obi-Wan Kenobi, which can be addressed by allowing the Grand Inquisitor to survive (though a definitive death would pose much greater problems, considering his significance in the animated series).
Star Wars Rebels has provided some of the best storytelling in the Star Wars universe, presenting both exhilarating action and profound emotional resonance. Consequently, coupled with the evident love from fans of the animated series that prompted the addition of various live-action Star Wars characters from animation, Star Wars Rebels is certainly considered canon and is unlikely to be removed anytime soon. Certainly, this does not mean that mistakes can't happen that 'breach' canon, as demonstrated by George Lucas' original and prequel trilogies. Nevertheless, considering Dave Filoni's significant impact on the future of the Star Wars franchise, it is clear that Star Wars Rebels will stay important in the coming years.