End Game Minecarts

Since Mojang has stated they want to make minecarts useful in the end game, here are a few suggestions that would buff minecarts, while still making them balanced. First, increase the default speed, not by much, maybe to about 10 blocks/s. This would make them faster than sprinting, while not making it overpowered. A second thing would be to add a faster variant of the powered rail. Several players have had the idea of a 'copper rail', I think this would be a perfect change. It increases the speed, while also giving players an incentive to mine copper. The speed shouldn't be incredibly fast, maybe 75 blocks/s. This makes it fast enough to rival ice boats, and make gathering the tons of recourses well worth it. To balance minecarts, they could potentially take longer to gather speed the faster they go. Another suggestion would be to make the copper rails only be powered by a special source, maybe a copper lever, of some sorts. Hope any of these suggestions help!