Greg Johns makes it sound quite possible or even probable, while Jon Heyman makes it sound like a done deal. Ben Gamel's oblique has him out for an admitted 4-6 weeks and you know what the consensus of the Denizens is on this injury.
Dr. D had always thought this would be a fun solution to the M's outfield depth, provided of course that Ichiro doesn't insist on 550 AB's. Obviously he doesn't, since he's been at 215-438 the last four (4) years.
The Mainframe warns not to let Ichiro's slash line (.255/.318/.322) in 2017 fool you. For one thing, he went .309/.398/.393 in the second half, which full-season would have been his best since 2007. For another thing, he's been bouncing up and down on the batting average for 5 years. A return to his original MLB home could be just the thing to energize him.
Ichiro swears he'll play MLB until he's 50. HQ notes that his SX finally dropped from the 135 level he'd sat at for many years to about 89 last year. Strangely, they project him conservatively at 117 SX next year. As SABRMatt points out, an injury can drastically take out your SX. Dr. D enjoyed watching Rickey play here at age 41 and although it will be age 44 for Ichiro, it's safe to say that the lighter, more balletic Ichiro should project to perform better past his 40's.
HQ also complains about the 1 in Ichiro's SB column, but his opportunities were down to 3% (from their normal 15-18%) and his actual SB% at 50%.
Here is Lookout Landing's take on the situation, a quite useless twenty sentences' worth of "ahahahahahaha!" while allowing that it could work. (?!) Here is Fangraphs' more serious article on the subject. They also clearly state that they have no idea whether he'll play well, but gingerly guess that he'll play at replacement level for a few months (0.0 WAR) and then retire with dignity.
Dr. Detecto does not cover his behind by straight-facedly allowing for 12 different possibilities: our prediction is that Ichiro will reach deep into his Safeco soul to produce. A .280 AVG and plus defense, with basepath contribution, would set Ichiro as one of baseball's best role players, at least for the first half.
As Greg Johns points out, the Mariners are a team open to bringing back aging team stars, such as Griffey and Vizquel almost came back. Also they're not at all averse to aging non-team stars such as Mike Sweeney. Then again they're big on Japanese players, with the best example being their persistence in trying to rehabilitate Hisashi Iwakuma.
The Mainframe guesses that Ichiro still has the needle at about 1/8 to 1/4 on the gas tank, as he adjusts the magic wand towards pool-cue singles through the left side and wrings whatever kinds of singles are left out of the towel he's swinging. I guess you and I would have to wait and see -- in his first ST week -- whether HQ is right about his legs being gone. It would surprise me if that were true.
But watching Ichiro have a .300/.400/.400 half season in Safeco Field, while running down gappers in RF, now that would be my idea of a fun consolation prize for a lifeless winter.