The game isn't shut down? Is it?
Don't think so, but it seems like they stopped supporting the game a while ago with new content.
I just took a quick look at this link where it shows the characters and their release dates:
These are the current prices, but you can view the Hero price history to see when prices have changed.
heroesofthestorm.fandom.com
2017 - 15 new characters
2018 - 9 new characters
2019 - 4 new characters
2020 - 2 new characters
2021 - nada
Personally, I got a hell of a lot of hours out of this game. Played tons with my friends. However, I never actually spent a penny on it, lol. I just used whatever free characters they had available at any particular time and used the in-game currency to buy any specific heroes I liked. Never used any real money.
Which in a way is pretty bad. As weird as this might sound, I think I would have gladly paid 10-15 bucks for a "Battle Pass" every few months. When a dev team actually churns out some consistent content and I am getting hours upon hours of decent play out of it, I don't mind supporting them with some money. I feel like there was no reason to spend a penny on this game if you were just a casual player. Probably not a good sign...
As for the game itself, I did like how different each hero felt. The way they adapted certain Overwatch characters, for example, was really cool. Was hoping to see more of that, but then they just stopped supporting the game. Probably because people like me didn't spend a dime, lol.