10 billion is the result of savings discounted at 10%...but in reality you get the groupon rate for the rest of your life and your children's - patents are good for 20 years at 100%. That was what 'enterprise' value or perpituity is all about...tomorrow.
"We estimate Apple will ship ~500M phones in the next four years. Assuming a 5% unit CAGR thereafter and a 10% discount rate, the InterDigital portfolio could be worth between $3B and $10B to Apple,"
Also "InterDigital's patents could save Apple $3-$10 per handset and could substantially increase the price of the low-cost Android phones launching in H2:11," Apple could increase Andriod's handset costs by 3 to 10. Now the net impact may be doubled!
hope this helps...BB

"The world is a dangerous place to live�not because of the people who are evil, but because of the people who don't do anything about it." �Albert Einstein