The problem with this is that if you hive off the 80 percent that is easy and profitable you may also end up binning the competitors and then there is nothing for the 20 percent if the new competitor decides to do absolutely nothing.
This is what happened when Craiglist and later Facebook cannibalized classified ads in the US; many local and hyperlocal newspapers disappeared because they were not big enough to attract major advertisers, but all the local ones left. Yet Craiglist provides no news at all and Facebook aggregates news but certainly doesn't produce any, and especially not at the local or hyperlocal level.
This is what happened when Craiglist and later Facebook cannibalized classified ads in the US; many local and hyperlocal newspapers disappeared because they were not big enough to attract major advertisers, but all the local ones left. Yet Craiglist provides no news at all and Facebook aggregates news but certainly doesn't produce any, and especially not at the local or hyperlocal level.