Not a whole lot. I think 5% is a very accurate figure for the current implementation. However, if MS changes a few things about the way UDTs and UDAs work in the next version, I think that number could jump quite a bit.

I also predict that in a future version MS will implement a fully object-based data access library that can compete with TSQL from a performance point of view. Note, I have no inside information to back that up, it's just what I think I see based on some of the direction I see all of this going in. If that does turn out to be true, I think we'll see the landscape drastically change as developers really will no longer have a huge incentive to learn T-SQL. But that's at least a few years off.