Lets assume for the sake of argument that I have the following tables in a single SQL Server database.
mySchema.Users mySchema.Products -- secondSchema.Users secondSchema.Contracts secondSchema.ContractItems -- oldSchema.People oldSchema.Table1 oldSchema.Table2 oldSchema.Table3 oldSchema.Table4 -- and so on and so forth
Each "schema" is fully independent of the others. The only reason they are in a single database, is due to hosting and cost limitations. In a perfect world these would have been in separate databases to begin with.
What things will I need to do when (and if ever) I need to move secondSchema into a new database, all by itself because its usage goes up and it now requires being housed in its own database.
I have reviewed Decision criteria on when to use a non-dbo schema vs a new Database, and as I've stated above, there is no relational or transactional justification for them being in the same database. They are in there for cost reasons.