As much as I love visiting the old, traditional grounds like Welford Rd, commercially it makes no sense at all to have 2 separate sports clubs, each of which only needs use of a stadium on alternate weeks for about 9 months of the year, operating on each other's doorstep. From that point of view, Bristol probably have the right approach, with a single umbrella organisation running both Bristol Rugby and Bristol City football out of the same stadium. Wasps under Chris Wright tried the same with QPR at Loftus Rd, but not so easy when you don't have that shared identity of the city. London is too vast and tribal in sporting terms to pull it off. We now have a different problem in Coventry where we are viewed by some as the cuckoos in the nest without the shared history in the city.
Emotion and tradition in sport count for a great deal though, so simply packing up Welford Rd and moving up the road to the King Power will be pretty universally unpopular, however commercially sensible it may be.