With US 10 being upgraded to 4-lane, there will be several highway reroutings and jurisdictional transfers taking place over the next couple of years. The most obvious is US 10, which will follow I-39 north to it's new alignment which is about where the former CTH X interchange was.
WIS 13 is being rerouted to make use of the US 10 alignment as well. (I do question why it WIS 34 will be kept when WIS 13 is rerouted along it though - but this is obviously (in my view) a Wisconsin tradition.)
Details of the changes -> http://www.dot.wisconsin.gov/projects/us10/changes.htm (http://www.dot.wisconsin.gov/projects/us10/changes.htm)
Very interesting. Not much more I can say than that, besides that it will probably raise the question (again) of whether I-39 will be extended or not as well.
Many highways were rerouted, moved, extended, etc - with the US 10 expansion near Appleton, WIS 76 and US 45 were also rerouted - and WIS 15 was resurrected for the third time.
THREE times? Have all the WIS 15s been in or near the same places?
I have seen other maps that do not include a multiplex of Wis 13/Wis 34 but like you said, it would not surprise me because of the "Wisconsin tradition" (which I really do not like). Also, I sort of wonder if the northerly extension of Wis 80 would have been better served as a southerly extension of Wis 97...six of one/half dozen of the other I would guess.
No, the three Wis 15's have been in different alignments. Read all about it here: http://www.wisconsinhighways.org/listings/WiscHwys10-19.html#STH-015 (http://www.wisconsinhighways.org/listings/WiscHwys10-19.html#STH-015)