I started with fish in the late 60's, and my memories of water changes were quite the opposite; my first tank was a metal-framed 5 gallon perched on a tiny table in the corner of the living room, and under my father's watchful eye, it suffered through a complete 100% change every week. This included all the fish and plants being removed into a bucket, with all the gravel, decorations and the tank itself being thoroughly scrubbed with clean water, and then re-filled with fresh. The new water came from the tap, and was drawn the previous day and sat in buckets to allow the chlorine to gas off. Chloramines were unheard-of.
Maybe other folks avoided water changes, I dunno...but back then we didn't all have instant access to everyone else's most casual fleeting thought or idea as we do today. My methods weren't a result of the "common knowledge" of others; my Dad (who was not an aquarist himself, just a father supportive of his son's interests) assumed that this was the way to keep a tank clean and healthy, and it was a number of years before I began reading enough to learn differently. In fact, I'm not so sure I did learn it; I still tend to do a lot more and a lot bigger water changes than many folks, and there's no doubt that it stems at least partially from those days.
Aquariums in two or three thousand years? Personally, I think that's a pipe dream. Look at the changes in technology, society and the planet itself in the past couple of millenia, and observe how the speed of change has increased. If we still exist in three thousand years, we will be so different as to be a practically a separate species; probably just shapeless blobs of goo embedded with bits of micro-miniaturized hardware so that we can continue to be instantly and continuously connected to each other. Mustn't miss a chance to inform the world...with pictures...every time we eat a burger or buy a coffee.
Of course, by that time, we probably won't eat, because nutrients will be introduced by means of a Star-Trek-like transporter directly into our bloodstream...and we won't need to talk, since we will all be linked in to the Collective Internet Hive Mind...so we won't have mouths anymore. We won't need to use bathrooms, since the same technology will transport waste molecules out of our bloodstreams in a similar fashion...so there's another couple of orifices we won't have anymore.
We'll just sit and vegetate while our minds wander in our virtual fantasylands.
And we will be so self-absorbed that we won't have time to worry about the fact that there probably won't be any other living species around to keep as pets, or in aquariums. Occasionally, a piece of automated construction machinery may unearth one of the last remaining earthworms or grubs...and we will ooh and aah and fearfully keep our distance until the killbots arrive to dispose of it.
Of course, there's a good chance that actual intelligent life may have discovered us before that time...in which case we may find ourselves in a quarantined world aquarium, kept safely isolated lest we become the interstellar equivalent of Zebra Mussels or Brown Rats...i.e. an invasive and destructive species that must be controlled to keep it from totalling screwing up any environment it manages to access. Or maybe they'll just decide we're too much trouble to keep around...
Yeah...I miss the 60's...