And by making a faster train, your not solving this problem because it will simply take longer for things to get to that point. In other words, it's a band-aid fix.The problem isn't that the trains don't get resources back before I run out because I don't have enough trains, it's because it takes nearly 10 minutes for my trains to get to my closest ore outposts, since I depleted all the closer ones, and I know this is an issue many people see with long time maps.
Edit: However, band-aid fixes are not bad if they actually add something to the game, especially in a sandbox game such as Factorio where it's only a matter of time before any solution does not work. Take Angel's Smelting, for example: It provides an alternate ore-processing chain that allows you to increase the yield from ores. While you eventually return to the process of simply scaling up to produce more, the mod itself adds more depth to explore before you get to that point.
I will also say that I like some of the ideas you have for train cars as those do add depth.