In a default installation of Plesk they make it very easy for you to add additional MySQL servers (there are options available, such as: "force database creation on remote database servers rather than localhost").
While Parallels has multiple products available for "distributed systems" these are generally products which were acquired and they will be discontinuing in the future.
Generally, we run our clients e-mail and DNS through systems which are completely separated from Plesk. While it's not our standard operating procedure, we did provide support to a client who used a script that would update their 3rd party DNS via API every time a change was made to Plesk's DNS records.
We knew PBA but that was very very costly and was intended for telcos.
We need to distribute all the services, not only email or dns. Dns is already distributed but we need to separate web, email, ftp, mysql. The user will access to his panel but all his services are separated.
I am checking the Plesk Automation but i am not sure if this is the old PBA software.
Are you sure Cpanel had these features like distributed service, load balancers? I don't remember thay they offer such a thing