I honestly do not think it gave anybody the idea of it being a future based ride ever, it was more like an adventure that even nowadays is expensive as a ride (private submarine tours) and that has always been a road of exploration of our planet that is the last frontier.
The concept of a ride in a submarine is good immersion (pun intended) plus it has a historical anchor to one of Disney's more cinematic achievements 20K Leagues Under the Sea released oh so many years ago.
Immersion into space rides may be in the future, matter of fact I have recently read Red Mars and just now starting on Green Mars and will finish the trilogy of Blue Mars. These are mass paperback scifi bestsellers that cronicle the terraforming, colonization, and the future of Mars as it evolves while Earth becomes uninhabitable because of our drain upon natural resources and the effects civilation has had upon the climate, the aftereffects of massive global warming and such.
Which kinda makes me more interested in the dramatic weather changes happening across the US, tornadoes in CA, arctic weather in the plains, a drier Seattle and last but not least the extreme rise in temperature where I live up here in Alaska. its becoming more moderate in our winters, no more of the -50 and -65 winters, the coldest has been a few days around -15 to -20 plus we are getting more rain and the summers are actually getting well over 85 degrees!
What does all of this have to do with submarines? If the worlds oceans rise, which they are...and we cannot easily migrate off planet en mass then the logical step would be to construct floating cities and underwater harvesting, mining and research centers. The earth may never become a "Waterworld" but with 85% of the population living along the low area coasts it inevitable that either we retreat to high ground or adapt.
So 50 years down the road, Disneyland is celebrating its 100th anniversary, would a submarine ride about fish and turtles be popular as it was now? And if DL is still above water would a ride or show being more suggestive of a future where sub travel is as common as commuting from one undersea habitat to another? When the atmosphere becomes unbreathable or the ozone layer has broken down to the point that being exposed on the surface is fatally dangerous then where to?
There is another diection the imagineers can take, similar to the SeaQuest idea. Or the ride can stay in history like an Atlantis theme, or fantasy like in Nemo, but however the Subs are more in TL so its suggestive of playing upon a futurity based theme, logically you would think.... :confused: