Unforunately, the retry work was never completed and has been on the back burner for the last couple of years. A large part of the functionality was implemented, but there's still a lot that needs to be done, and there are some integration issues with things like stats.
I do want to get back to this at some point, but it's not clear exactly when that will happen. But I suspect that it will wind up coming up again in the context of the xDS work we've been doing, so this may wind up getting prioritized again sometime toward the end of this year.
I'm sorry that I don't have better news to share on this.