Is Northwest's move just the beginning?

Yesterday Northwest announced it would charge $15 for some seat selections. Now airline expert and Cheapseats.com spokesperson Terry Trippler is predicting it's just the beginning.
Trippler says in an email, "Emergency exit rows can probably earn them more than $15, so I expect to see that amount increased." He goes on to say, "I believe a $1 to $2 charge for sodas and juice is coming [to the airline industry], but the most controversial issue will be when the first airline announces a charge for checking baggage. I believe it's coming and it's coming in 2006."
Unfortunately there's already precedent overseas. British low-cost carrier Ryanair announced its own
charge for checked baggage
earlier this year.