Here’s the deal, the pro scene, the Heroes Global Championship (HGC), got cancelled by Activision and some of the developers were relocated to other projects (although we have confirmation that a lot of the more talented devs are still with the team). Also it was announce that the cadence of content release will change - slow down.
Now, what does this mean? Well considering the HGC and the twitch streaming community were the only advertisement the game got this means HOTS will no longer get any advertisement. This means less new players like yourself will join the game, a.k.a the game will stop growing.
In summary: No, the game is currently not dead, but it’s future is not bright either. Considering that Activision is adopting a new policy of cost cutting 2019 will likely not be a good year for the game as well.
Although I personally still enjoy the game and will continue playing it in the future I cannot, in good conscience, lie to you that the game is fine and that it’s future is bright, because they are not.