The plotly R package is a tool that makes the Shiny and the RMarkdown/Quarto HTML formats truly shine. According to this community announcement, the Plotly organization is preparing to retire R documentation in November 2025.
While there may be alternatives for time-series data like dygraphs, and newer projects like ggiraph are taking a stab at interactive plots as an extension of ggplot2, the rgl package provides a low-level, flexible 3D plotting capabilities, other interactive GIS libraries provide good mapping tools, and echarts4r (new to me as of today) shows promise, no single package is as widely used or comes close to the providing the capabilities (and rendering performance) that the plotly package does today for interactive visualization. Just based on Stack Overflow question volume (I know, I probably sound like a dinosaur) , plotly is used at least an order of magnitude more than any of the alternatives mentioned above.
To say the least, losing this part of the R ecosystem would create a hole that might not be filled for some time.
It would be fantastic to see Posit pick up the torch and host the documentation (or even support more maintenance efforts to get the R plotly documentation back up to date) in a similar manner to how it supported the "tidyverse" - perhaps just wishful thinking on my part though.
I have opened Issue #2456 on the Github repo for community discussion.
Related thread on reddit.