I'll just note that if a new developer takes over, he owns the property in question and can make any changes he wants to, although there may be limits(*). This scenario was very common during the Great Recession/housing downturn in 2008-2012, and it is a risk you take whenever you buy in a community that is still under development.
(*) These changes can affect the types of homes being built - for example, the newer lots are smaller and the homes are cheaper. Or the planned pool and clubhouse won't be built, and the proposed site for these amenities are developed as lots for homes. Or - probably worst case scenario for existing homeowners - the vacant property is re-zoned commercial and you get a strip mall and gas station next door. All of these things are possible. Developers are in the business to make money, and if the previous plans for the vacant land are now less profitable, then the developer can change what will be done. With luck this new developer will listen to current owners' concerns, but I wouldn't be too surprised if he didn't. If I were a current homeowner, I'd listen to what the developer says and make my own plans accordingly.
By the by, there was
an article in yesterday's Washington Post about the changes to homes being built by the nation's large home builders. The newer homes are narrower, smaller, have fewer windows and doors, and have less cabinetry inside. This is partly in response to the sharp rise in housing costs recently, which has priced many people out of the market altogether. So developers have made changes to what they're building - it's either that, or their businesses are no longer profitable. The article mentioned that townhouse-style construction is increasingly popular, so HOAs/condo communities aren't going anywhere. (Article may be behind a paywall.)