Docker Swarm isn’t dead as of now. According to what Mirantis has to say; the company bought Docker Swarm EE in 2019. Mirantis has declared that it would drop Docker Swarm mode as-a-service after a support period of 2 years. And thus are slowly reducing the developments in the Docker Swarm and probably it would halt and could potentially be replaced.
Docker Swarm mode will be alive and no change for that as of now according to the insight gained from Mirantis as they are added in the latest version of docker-CE (community edition). The only change would be the dropping of Swarm mode as-a-service.
If you are planning to enter this domain, then it's better to start off by getting yourself registered for Docker training from Intellipaat.
Also, I would suggest you watch our YouTube video on Docker training if you wish to know in-depth about this domain.