That's possibly true. Perhaps the only real saving with the trains is that the same scene of a train going through a stargate would get re-used more often than the guards walking their posts outside the entrance to Cheyenne Mountain.
The Stargate Ecosystems idea (way upthread) was a way to revisit the old elements of the show, expand on them in a greater variety of ways, and allow for different types of ships and technologies in the isolated "mini-universes" hidden in our own galaxy. There are some ways it could cut some of the production costs, but not very many, and not ways that probably weren't already being used.
The Stargate Futures idea, while allowing for a wider variety of human-centric plotlines (more "Earths" to get invaded, etc) seems more limited in alien interactions because it doesn't directly leave room for many aliens, especially if it takes place in the galaxy as SG-1 and SGA left it, rather depopulated of enemies and threats.
Perhaps the "Futures" idea should be folded in to the "Ecosystems" idea, somehow.
*thinks a minute*
You could have our modern SG teams visit an ecosystem where Ancients had dropped off early humans, who then expanded to that level of technology. Then the arc could play itself out without dragging down the whole franchise, which it could if Cargate was the entire premise. The teams would just start visiting a more interesting ecosystem with warp capable starships or something.
You could have them jump to the future for a long story-arc through the Cargate universe, then find a very good reason to jump back and alter the future. Perhaps splitting humanity up into hundreds of enclaves based on religion and politics turned out to be a very bad, bad idea, or perhaps things were working great until they did something very stupid.
Or you could have a universe where the primitive humans had some kind of window looking into our world, like sentinels from the gods, and their hundreds of planets slavishly copied everything they saw being built on Earth, at least as best as they could. That would explain why so much of what they built looks exactly like things and locations here. Of course that sounds like a bad version of Galaxy Quest mixed with some Star Trek plots about societies run by computer overseers, and I don't see viewers really buying into it.
You could follow up with the logical path of Ba'als character, and have a system lord with a vast empire who thinks "If you can't beat them, join them, and if you can't join them, copy them," knowing that if the hundred worlds of his domain think, act, and innovate like Earth, they could crush us. The shortcut through that arc could use the Asgard time-compression device so his worlds achieve parity with us in technology and per-planet population in just a couple of years of our time, with the added threat that they're also using Goa'uld weapons technology. That story might have enough legs to relaunch a series without other supporting elements (like the ecosystems), but eventually something new is going to be needed, given how Stargate first fights and eventually defeats its alien threats.