Will this be Ken Griffey Jr.'s final season?

Mariners beat reporter Geoff Baker of the Seattle Times expects Ken Griffey Jr. to retire after this season, writing:

Yes, I think this is Griffey’s final month. I think the team hopes so and I do think he is coming to realize it as well, even though, I’m sure, he’s going to miss the day-to-day reality of life in the big leagues. Well, he’ll miss some of it, anyway. He won’t miss what he went through yesterday, having an MRI done on a swollen knee. [...] Some fans had envisioned Griffey playing the field this year. Well, they were wrong. As the Mariners found out very early, playing Griffey in the field was a recipe for health disaster because his knees couldn’t take it. Now, he’s struggling to even fill the DH role on a daily basis. It’s time.

Griffey has been able to play just 83 innings in the outfield and he’s hit just .221/.329/.399 in 377 plate appearances for a .728 OPS that ranks third-worst among AL first baseman, corner outfielders, and designated hitters ahead of only Aubrey Huff (.703) and Mike Jacobs (.705). On the other hand, I’d never criticize or mock great players for wanting to stick around after they’re no longer great, and Griffey still has some power with 14 homers and 15 doubles in 321 at-bats. If he wants to play another season as a part-time DH and maybe try to make a run at 650 career homers, then why not? However, as Baker notes there’s little chance of the Mariners welcoming him back for 2010. Griffey was a good fit this season, as the new regime wanted to clean up the mess of 2008 and create some good will among fans in the process, but the Mariners will be far more focused on contending next season and can easily upgrade the DH spot.