It's a natural progression. The industry grew and prospered during favorable times. But the industry has apparently entered its final, exponential phase, where competition has become very fierce. The market simply doesn't need so many land-based casinos. Land-based casinos certainly have certain advantages over online ones, but these advantages are vanishingly small. Although for those living nearby, it was probably convenient. I think many online casinos will also close. The gambling craze will cool somewhat, and many will move on to other gambling areas.
One thing about managing a business is that you need to go along with the flow and evolve as others are doing, because without that , it's near impossible to stay in business.
Online casino is gradually taking dominance from land based casino, since they are cheaper to manage than land based casino that most times have unnecessary expenses to pay, and truly online casino will also close down, but before an online casino closes, just know that five land based casino has already shutdown before then, but competition has made it very difficult for those that are not skilled in business to continue, and so i wouldn't be surprised if more land based casino shut down in the future.