Assume that everyone can search the internet all the time, no matter where they are and that you can't even tell whether or not they are doing it.
How do you test for comprehension? How do you test for anything?
The first option would be to give up on testing altogether.
The second option would be to create questions that aren't easily searched for- search de-optimization, if you will.
As people take the second option, because people like testing, even if it doesn't work particularly well, I think we'll see a move toward tests that test our ability to synthesize information. Assuming a fact-rich environment, the test makers most obvious strategy would be to give new information and ask the test taker to integrate the new information with the old information. Do that five different ways, and it's pretty clear you know your stuff.
Of course, there will be people on the internet attempting to provide solutions, but the test taker would have to have some level of comprehension to find them. The search wouldn't be like searching for the word eutrophic. Instead it would be a search for a relationship between two or more different sets of knowledge.
Thus searching for a legitimate answer to the problem would likely be more difficult than trying to come up with a plausible sounding answer on your own.