ARR relaunched FFXIV three years after its initial launch, when it was still very much a modern, arguably cutting edge game for the genre.
TOR is a decade old. The engine is full of technical issues. It looks dated. They could overhaul everything, but they might as well just make a new game. It would probably be less work to start from scratch than to try and retrofit something that was behind the curve ten years ago.
And I really don't think High Republic is where the money would be at. I know Disney is currently pushing it in comics, but as an outsider, it has like zero buzz. Even googling it right now it's only being talked about on a couple websites that churn out Star Wars and comic book related videos every day. Maybe The Acolyte Disney+ series will make people more interested, but right now it's kind of nothing.
It's too bad that the sequel trilogy restricts things so much, because "The New Republic" set in the time between The Mandalorian and the sequel trilogy would probably be super appealing to people. You've got Luke's new Jedi Order, the Sith Eternal, the remnants of the Empire, and the fledgling New Republic. You could really create a different dynamic where the imperial factions are now rebels and warlords, the Jedi and New Republic are doing reconstruction, etc.