I think you’ll need to be more specific, as every scaling problem is a specific problem–there’s no such thing as a generic “scalability” tool. If your application does not scale, there’s nothing Virtualmin can do to make it scale.
It is possible to cause Virtualmin managed web server configuration to be replicated to infinite many servers. In fact, it’s close to trivial. If web service configuration is the only element that needs to be replicated, then your job is incredibly easy. (shared /home on a file server, rsync configuration, possibly update IPs in configuration, reload Apache on slaves)
But, if you add an application into the mix, the problems balloon into spaces where Virtualmin (and any other control panel) cannot help you.
Database replication is still a complicated process with MySQL, and usually requires deep knowledge of your schema and sharding strategy. We support more capabilities in this space than any other control panel I know of because we have more powerful database administration tools in Webmin (and we support ndb cluster tables in MySQL…which are currently memory only tables, but they are replicated out to other MySQL servers…I don’t think any other control panel can manage these tables, or deal with multiple MySQL databases at all). Jamie is working on some additional multi-MySQL database features, as we speak.
so i will have to wait for ISPConfig 3 beta to get stable then.......
Perhaps. We’ll still be here when you get back. (The thing is, I’ve heard this kind of, “Well, I guess I’ll use X control panel instead of Virtualmin, because of Y and Z reasons.” And, a week or two, or a month or two, later, they come back after finding out that the alternatives were far less capable, despite the hype. I have nothing but respect for the ISPConfig developers…but we’ve got a several year head start on them. It’ll be a while before they catch up.) 
And, it sounds like you’re going to have to write a bit of code, anyway, to support your requirements. I’d suggest you have a look at the respective APIs of the products you’re considering, and imagine how much work you’re setting yourself up for.