Delta relents, somewhat

There’s been a lot of complaining about Delta‘s decision to downgrade the benefits offered to their most frequent flyers. I voted with my feet at the beginning of this year and have accumulated almost enough miles on NW for their midtier elite program, which gives me unlimited free upgrades on any fare class.
Today I got some mail from Delta announcing changes to their Platinum Medallion benefits for next year. (See a summary of the changes here.) The resumption of unlimited upgrades is nice, but it’s limited to the most expensive (Y, B, and M-class) fares. No thanks.
On the other hand, with Continental’s recent decision to backstab their elites, can NW be far behind? One speculation is that CO and NW are aligning the details of their FF programs with Delta, which means that it may be in my best interest to spend a couple hundred bucks on a mileage run to Singapore or Tokyo to make sure I hit NW’s top tier– if CO and NW both slave their upgrades to DL’s program, I’ll be in trouble as a midtier member.