Depends what you mean by relevant. This conference has some of the blue blood programs with the highest attendance and the most amount of money. So the Big Ten will always be relevant from that point, having a good deal of say so at the bargaining tables.
In terms of on the field performance, I think it is a huge up hill battle. Urban seems to have figured it out, but we will really see where they stand on the national scene in a week or two here. The problem is the entire conference is located in a part of the country that has little to no elite talent. Plucking the kids from So Cal Texas and the Deep South is harder these days because our schools don't really have anything to sell them on, while having worse weather and being far from home.
Imo, it is a serious problem and no clear solution.