Since this ban, difficult to enforce, will soon be lifted, dance clubs will see an opportunity to make more money by staying open later. They will extend their hours as soon as the ban is lifted, and patrons will extend their dancing into the night, glad to have their freedom after so many years.
If the ban was lifted, it was lifted because the dance club owners asked for it to be lifted. If they asked for it to be lifted, they are clearly planning on having their clubs open later. This is great news for the young generation of Japanese that want to stay out late having fun dancing.
With the ban lifted, I cannot imagine that the clubs wouldn't stay open later. The later you are open, the more money you are going to make. It just makes sense to extend the hours, though it will be an individual choice made by the business owners themselves. I imagine most will decide to stay open later.
Dance clubs are popular with youth culture and most of Japan's youth have adopted western culture. Western culture dance clubs are open until the wee hours of morning and I believe Japan's will follow suit. If the market wants later hours for the dance clubs, there is money to be made. If there is money to be made, the dance clubs will be open later.