In a recent video posted to his YouTube channel, Super Smash Bros developer Masahiro Sakurai revealed that not only is he working on creating more content for his channel, but he is also still very much hands-on when it comes to game development.
While not much information is given, Sakurai does state that he is still actively involved in developing games. Additionally, Sakurai has never stated that he is retiring from Super Smash Bros development, nor that he wants to retire the IP entirely (something that Nintendo would likely object to regardless).
Furthermore, rumors about the Nintendo Switch successor are becoming more and more prominent, which means the next Super Smash Bros installment (AKA Smash 6) might be coming to the "Nintendo Switch 2" or the next generation of Nintendo home console.
It should also be noted that the team at Bandai Studio S posted a recent job listing for an upcoming game. A lot of this team also worked on Smash Ultimate, which could mean that development is in its early stages for a release in a few years.
While nothing is confirmed at this stage, it is still nice to see Sakurai doing what he does best: developing amazing games. Even if we have to wait a few more years for Smash 6 or anything else he cooks up, the wait will surely be worth it.