I don't remember when Riviera is closing shop. I had thought it was that 2024 was the final season, but I could be wrong. Little Turtle is not closing yet, but I have heard rumors that it's likely to close down and the property sold by the owner for development. It wouldn't surprise me if that happens at some point in the not-too-distant future. And I suspect the same fate will await Winding Hollow. I'm not saying it's right or wrong, but I suspect there's a lot more money to be made from developing the land, whether for commercial or residential purposes (the new Bob Evans corporate HQ is literally across the street from Winding Hollow), than from continued golf course operations.
Really, the only decent public options left in Columbus are GC of Dublin and Granville, IMO. There are a few others, but none that really make you want to play. Of course, there are some good options outside Columbus such as Longaberger (regardless of what some here may think, it's a fun course to play and features some really good land unlike much of central Ohio). For as much really good golf as there is in central Ohio, there's a serious lack of good public options.