What does Bilbo learn from the raftsmen's conversation in chapter 10 of The Hobbit?

When he overhears the raftmen talking, Bilbo learns that it is harder to get to The Lonely Mountain than they thought.

By this point, Bilbo is tired and a bit grumpy.  He has been through a lot.  He is also finally in sight of The Lonely Mountain, and getting closer seems to bring only more peril.

The Lonely Mountain! Bilbo had come far and through many adventures to see it, and now he did not like the look of it in the least. (ch 10)

Bilbo learns that there are problems in getting to The Lonely Mountain that he and his friends did not know about.  For one thing, “the roads out of the East towards Mirkwood vanished or fell into disuse.”  Not only that, even the banks of the river are treacherous because the Lake-men and the Wood-elves can’t agree on whose responsibility it is to take care of them.

Things have changed since the dwarves where last there.  There was flooding and “an earthquake or two” attributed to the dragon.  The path had vanished, and “marshes and bogs had spread wider.”  People have ventured in that direction and never returned.  Bilbo is not encouraged. 

Bilbo's instincts about the mountain seem to be accurate.  Now that they are about half-way through the journey, they can see that things are not getting any easier.

In The Hobbit, what does Bilbo learn from eavesdropping on the raftmen's conversation?

As Bilbo rides on his barrel shivering with cold and wasting away with hunger, he is lucky to learn a few tidbits of information that the "raftmen" share as Bilbo remains unseen.  The main thing Bilbo learns is that "those lands had changed much since the days when dwarves dwelt in the Mountain" (171).  In other words, the original plan of Gandalf and the dwarves would never have worked because, according to the raft workers, "only the river offered any longer a safe way from the skirts of Mirkwood in the North to the mountain-shadowed plains beyond, and the river was guarded by the Wood-elves' king"  (172).  Unbeknownst to Bilbo, Gandalf had found out this information on his own and was exceedingly worried about the little travelers.  "So you see Bilbo had come in the end by the only road that was any good," through no fault of his own (172).