What if you want to switch the data to point to say Oracle or MySql?

Well, that's what SSIS is for. ;)

Seriously, then you have to make some decisions. In many cases, a switch to a different database is a huge step in general, especially if you're abandoning a database where you decided to leverage many powerful features. But then again, why does an organization move to a new database?...among other reasons, to leverage many new and powerful features. ;)