I'd agree with this too but the idea of attracting Al Horford with precious little to offer is a bit less realistic than the chances of getting Josh Smith.
I would think you'd have to part with Rondo to get Horford, which doesn't seem worth it to me.
If it meant parting with Rondo to get Horford and we can be guaranteed of landing Deron Williams, I would do it.
Williams
Bradley
Pierce
Bass
Horford
Would be a nice starting five going forward with Stiemsma, Johnson, Moore, and two first round draft picks as a bench base to build depth upon. We might even be Eastern Conference contenders almost right away.