Signing Eric Decker would be a nice PR move in general, but the indifference shown to the Vikings by many Gopher fans that post here is not indicative of the feelings held by Gopher fans in the general public for the most part. The Vikes hardly need to cater to Gopher fans to get mass support from the fans or media attention.
Regarding stadium improvements, a big one that hasn't gotten much play would would be either the installation of a wifi network or boosters for the signals from AT&T, Sprint, T-Mobile, and Verizon. Most Gopher games play to well below capacity crowds, but you can still go minutes at a time without data coverage, especially at halftime. The Vikings will fill the house and overtax an already strained data situation. Their fans will want that situation improved and whatever remedies are employed will benefit Gopher fans as well and over a longer term.