I've heard the same thing from people at several level of the Twins' organization: Byron Buxton may not be the opening-day centerfielder, and Max Kepler may be rising faster than anyone outside the organization realized.
The Twins believe Buxton will be a star but there are regrets that they felt compelled to call him up last year before he was ready to hit major-league pitching. Kepler may be closer to being major-league ready, and if Buxton isn't on the opening-day roster, Kepler could be a factor.
If Buxton isn't the centerfielder, the Twins could temporarily move Eddie Rosario to center, which would open up leftfield for Kepler. Or the Twins could play Danny Santana in centerfield.
In other words, if the Twins decide to sent Buxton to the minors, there are a lot of possible opening-day lineups.
As I've been saying since mid-summer, the Twins do not plan to trade Trevor Plouffe.
Here's one way it could look (with me guessing what Paul Molitor would write down, not the lineup I would use):
Brian Dozier 2b
Joe Mauer 1b