Definitely keep the core together. Quite frankly, we don't know the next time we'll ever be this good again. For all we know, LeBron and Bosh end up on the same team, and after a couple years together and adding parts, end up winning 5 titles in a row, essentially negating any chance we have to rebuild around Rondo.
If they win this year (and I'd say even if they simply make it to the Finals), we should probably keep this core together another year.
Besides, there's only so much rebuilding we're going to be able to do with KG and Wallace here another two years.