No way they are going to waist the money for lawyers in a lengthy trial that they know they are going to lose, would be insane. Settle or buy, no other choice.
This is a very high stakes case, google is doing whatever it can to delay and obfuscate the facts as can be seen from the hundreds of useless motions filed.
It is also extremely rare for established older patents to be thrown out as Google is trying.
If this does not work they have very little defense other than that being some claims of different algorithms which they try to keep hidden from the public at large.