Good for the miners. It looks like they are pushing for higher fees.
If you give them 50BTC for mining the block, you better give them something comparable to record those transactions.
A transaction doesn't have a TTL, so if you store up a few thousand transactions with really small fees, you might be able to make a little money off of applying them all to one block.
Or, if you want to be abusive, you could save up all the free transactions and just record them all in one block many years from now.
Empty blocks should not be accepted if there are a certain number (value?) of waiting transactions.
This is the best idea I heard up to now. At least would keep the network working.
Accepting empty blocks is not a valid way to handle the situation, and their is no profit in doing so. Ignoring transactions is a way to signal users that they have to pay up. It would be great if miners had a way to advertise the price they would have accepted in fees.