> I also don't like how there looks to be an upcoming split in the plugin community when Vimscript 9 releases and the neovim community will ignore it while plugin authors in the vim camp (e.g tpope) may start moving their plugins over to it.

Honestly Vimscript 9 always felt like a serious case of "not invented here". Bram could have easily chosen one of many existing languages, but instead decided to take Vimscript and make it even more bizarre (this was even more so the case at first as IIRC block delimiters for example were really odd).

Setting that aside, you could also argue that people moving their Vimscript plugins over to Vimscript 9 is a problem on their end because it makes the plugins incompatible with NeoVim. In other words, the argument is basically silly.