Hi, Rionne. I'm not only not an expert on this subject, I'm not even semi-informed. I found one brief article from November 2017 by Leanne Pott for AARP that mentions a couple of alternatives. Basically they seem to fall into two camps: "green burials," which range from circa 1800s "just bury me under a tree" to more modern, controlled-environment, er, recycling in enclosed pods. The second camp is euphemistically called "water cremation," the one I said might be distasteful-sounding to describe. More specifically alkaline hydrolysis, it reads more like something a mob boss would have paid dearly to have had available in the 1920s and 30s.
There are already new companies springing up around "alternative interment," and I think we'll see that continue--probably worldwide--in coming decades. There's an idea if some entrepreneur is looking to startup a new business...
Bottom line, it's about the population and usable land. The annual population growth rate has been steadily declining since around 1988, but it's still a growth rate. In 1968 the world's population was growing at about 2.1% per year, and now it's down to roughly 1.1%. There are about 7.67 billion people alive, so that means we're still seeing over 84 million more births each year than deaths.
The growth is mostly urban, not rural. Meaning business centers and housing developments are using land that, in 1900, we might have had available nearby for cemeteries. In 1960, worldwide, the urban population was 1.02 billion and comprised 33.6% of the overall. At the beginning of 2018, it was 4.19 billion and represented 54.9% of the total population. By 2050, the worldwide population is forecast to be just a shade under 10 billion with 65% of us living in urban areas.
Genealogically, when it comes to burials things are a changin'. Here's a population visual I found starting at 1 AD (with the caveat that we all know estimating the population prior to the 18th century is pretty much nothing but guesswork):
Me, I think I'll hold out until burial-in-space becomes an option. Not that necessarily--other than cost--the notion would be entirely free of its own drawbacks...
"President Harriet Chandler signed into law today the so-called 'Space Reclamation' bill that will bar operations of SpaceX, Geoverse, and others that launch remains of the deceased into space as a form of perpetual interment. The hotly debated but eventually bipartisan passage of House Bill 4334 came after the destruction of two defense department satellites upon impact by orbiting, encapsulated remains, as well as the disturbing incident in 2025, termed the Charon Meteor Shower, where fourteen such remains partially survived re-entry with scores of objects impacting the area in and around Riverside, California..."