Firstly, your in a fantasy world (and I'm sorry to say limited of your knowledge in electronics) if anybody other than a large company has the ability to create such a card.
Secondly, your suggesting that a 10mm^2 chip will produce 1 TFLOP, where is this data from?
The GPU in the iPad is 25.6 GFLOPS (
http://www.anandtech.com/show/6324/the-iphone-5-performance-preview), so where is this 10mm^2 going to produce 1 TFLOP?
Thirdly, the die itself might be 10mm^2, but all the supporting electronics, connections, memory subsystems and what not takes up space and costs £££. Why do you think Intel and AMD are moving more and more of the things that used to be on motherboards (Northbridge, Memory Controllers, etc) to the CPU itself?
Finally, 10 dies != 10x the compute performance. You have overheads, limitations in the PCI-E interface, extremely limited driver set compared to current cards, etc, etc, etc.
If there was a market for this, somebody would have done it already.
Sorry to burst your bubble!!