Abstract classes in SQL Server. Are they even possible?
There is nothing like this in SQL Server. 

What tool are you building and maintaining your schema in though, will you be using database projects? If you went the "manual" method, while there is no SQL specific templating for this in SSDT, you might be able to use T4 templates to do something similar.

If that interested you then another alternative for templating is to use BimlScript. It is used to programmatically generate SSIS packages but they've very recently started doing something similar to generate SQL DDL so you could check into that.