Those estimates are not delusional by any means. First of all, remember they are talking about computing and not gaming performance. As much as people like calling Fermi a flop, it is not, not at all. Sure it's not as good as they thought it would be in gaming and power consumption, specially GF100 which is horrible, GF104 is much better, but Fermi was made with one purpose and that is to serve 3 markets as best as posible while spending as less in R&D as posible.
Now, take a look:
^^Is or is not Fermi (Quadro 5000 and 6000) a lot faster (2x to 4x) than GT200 (FX4800) -and while we are at it- Cypress (V8800, V9800) at the one thing this particular GPU was mostly designed for? And if anyone actually saw the keynote webcast, that's not all. iRay is amazing, it's an almost "instant" Mental Ray renderer that's going to make our job soooo much easier...
Also you can always have a bad chip from time to time, at least GF100 IS faster than Cypress, a luxury that AMD would have liked to have with the bigger than G80 (more transistors), extremely hot and power hungry R600, instead of being 40% slower than G80 when AA was used. And the thing is that R600 was the spark that initiated a fire that ended up on Cypress, it's not too far fetched to think Fermi and sucessors can do the same. At least the start has been similar, but at the same time better: it started better than R600 and like with R600 a few months later a refresh that does very well (RV670 ~= GF104), and unlike RV670, GF104 is not made on a smaller process.
Like R600, Fermi has a very strong uncore designed to last 2-3 generations, unchanged. Hence right now the uncore is very bulky and the core/executing units are very weak. Now we know that the architecture initiated by R600 needed somewhere inbetween 800 and 1600 SPs in order to give it's best, if Fermi is similar we will have to wait until it has 2000 SPs before any judgements are made.