There is zero reason why Wade couldn't play every day on the MLB team, then go back down when Buxton gets back.
Also, Buxton, Kepler and Rosario are all here at least 3 more years. What is his future here, if not 4th outfielder?
Not pretending to be "in the know" here by any means, but I'd offer a point and counter-point here:
Pont: He's coming off a fine season at AA, tearing things up there again, and he should already be at Rochester. His defense has to be better than Grossman, he offers, potentially, as good or better offense, and he could play almost daily until Buxton is back allowing for better roster/lineup flexibility.
Counter-point: He's only 24, about the right age for AA, is only beginning his 3rd full season of milb, seems to be developing more power this season, would require another 40 man roster move, there may be some small issues in regard to defense or beginning and the like the Twins are waiting to show improvement. (I may be mistaken, but wasn't he a little light vs LHP last season?)
Not arguing for or against his being brought up at this time. I'm glad to see Gonsalves and Littrell up at AAA quickly, and hope to see Gordon and Wade both join them very soon. (I think the Twins have been very aggressive with Romero). I just think there are a lot of moving parts and scenarios to be considered other then "promote him and play him as a regular for the short term because he could do better than what's filling in now." Not even sure we'd be having this conversation if not for the unfortunate injury to Granite.
If the Twins have been slow in promotions this season in any way, I'd say it's in regard to the pen. I just don't have long term faith in Magill or Hughes and I think I'd rather rotate through the AAA roster for those final 2 spots until someone takes hold of the job.