Hmm....
They're really trying to launch the 'new generation' as much as possible. We see this in all the TV shows and in the MnSG PV.
Yuko probably has one of the best career opportunities outside AKB48 as she's a great actress and is always entertaining during variety/talk shows, so it wouldn't be that surprising if she decides to step down relatively soon.
It is still likely Yuko will win the election and I'm sure she'll give it her all in AKB48 for the upcoming singles. However, I doubt she'll be in AKB48 for longer than a year. On the other hand, perhaps she can find so much joy and opportunities as being "the new face" of AKB48 that she'll ride it out even longer.
Yuko is definitely a highly valuable asset to be group, both on and off stage, so hopefully she won't leave too soon. It's tricky, I mean, if she's not happy anymore in AKB48 then I would have no problem with her graduating. If she still enjoys it then I wouldn't mind seeing her for years to come. Bottom line, I don't want her to crack under the pressure that may fall on her shoulders when Acchan leaves.