I find myself making convener belt systems that supply both coal and iron on the same belt, though, i repeatedly find that when it gets backed up, production can be halted at some point.
I propose, lane swapping technology!

The first lane swapper just switches the lanes of an object, there may not be much other use for this other than organization or just plain looks, but I would find it useful in some situations, like when you have iron being placed onto a conveyor by an inserter, but coal is already in that lane. There may be more uses to it that i can't think of currently. The more useful counterpart, and the reason i made this mock-image is the smart inserter. It would allow you to choose which item goes into which lane, it would be useful for helping things not get backed up and halting production because the iron ore is blocking the coal from getting to the furnaces, it also makes things tidy.
My second proposal is to add some difficulty options in the world gen menu.
Some examples are as follows:
[ }Hardcore (dying deletes save)
[ ]On death you drop inventory for later pickup
[ ]On the destruction of chests, furnaces, etc. Both the structure and the items within it are dropped as items for later pickup
There is already an option for no aggro, i think we should have more difficulty ratings, to provide either more challenge, or make it a bit easier!