I thought LightTable is an IDE, not rethinking programming :) Anyway, great thinking, I've actually come to a lot of the same conclusions. I'd suggest an inspiration: spreadsheets. Can you implement the separation of data model from indexes/optimizing physical model in an ad-hoc spreadsheet-like UI? When thinking "spreadsheets" you should think about not just Excel, but also Lotus Improv (which is a more structured spreadsheet, which is both a strength and a weakness).